RE: skinny power cords.
Effective January 1, 2002. Arc-Fault Circuit-Interrupter (AFCI) protection devices will be required for all 125-volt, single-phase, 15- and 20-ampere receptacle outlets installed in dwelling unit bedrooms (1999 NEC). The 2002 NEC requires AFCI protection for all 125-volt, single-phase, 15- and 20-ampere outlets (not just receptacle outlets) in dwelling unit bedrooms. For more information: http://www.mikeholt.com/Newsletters/AFCIs.htm http://www.ul.com/regulators/afci/index.html http://www.ch.cutler-hammer.com/ and search for AFCI http://www.arcfault.com/default.htm http://www.geindustrial.com/industrialsystems/loadcenters/notes/moreafci ..htm http://www.geindustrial.com/industrialsystems/loadcenters/notes/afci_pap er.htm Sincerely, Mark E. Bushnell, Senior Electromagnetic Effects Engineer Raytheon, Greenville, TX http://www.raytheon.com/ais/aisproducts/ais_mstf/emeffects.html This message is printed on 100% recycled electrons. -- Yes, This the reason that the arc fault interrupter was invented. New codes require it on bedroom circuits I understand. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
My apologies to Andrew Carson! Somehow I scrolled down so that only the Cc: for ron_wellman was visible and, therefore, typed in the wrong salutation. This would not happen were we writing letters in long hand; however, we would also not be addressing so many people at the same time. I am impressed that it takes a guy from England to tell us folks here the chapter and verse where to find things in our own electrical code. Let's hear more of such from over the pond! taniagr...@msn.com - Original Message - From: Tania Grant Sent: Monday, October 29, 2001 7:39 PM To: acar...@uk.xyratex.com Cc: WELLMAN,RON (A-PaloAlto,ex1); emc Subject: Re: skinny power cords. Ron, Thank you. I appreciate the reference to the NEC! taniagr...@msn.com - Original Message - From: acar...@uk.xyratex.com Sent: Monday, October 29, 2001 4:09 AM To: Tania Grant Cc: WELLMAN,RON (A-PaloAlto,ex1); emc Subject: Re: skinny power cords. Tania The V in SVT does indeed stand for Vacuum and not Vinyl. In reference to the Trade name of this type of cable being Vacuum cleaner cord not suitable for hard usage. Article 400 of the NEC, page 70-211 to 70-224 ( in the 1999 edition) defines all the US cordage definitions. What the letters mean and what use the cordage is suitable for. Tania Grant wrote: Ron, I am a bit confused;-- you stated " SVT is for vacuum cleaners, not consumer products."Is not a vacuum cleaner a consumer product??? I may be wrong, but I thought that the "V" in the SVT designation stands for "vinyl", a soft and flexible insulation. Since many vacuum cleaning cords are automatically wound inside the appliance, that suits the application quite well. SJT cords, on the other hand, are more stiff; however, they are also used with consumer products. Perhaps someone else can shed more specific light on the various U.S. power cord applications and their respective nomenclature. I know that in the SJTO designation, the "O" stands for resistance to Oil, and that such cords are recommended (required?) in industrial areas where oil would likely be present, such as in car garages, etc. Tania granttaniagr...@msn.com - Original Message - From: WELLMAN,RON (A-PaloAlto,ex1) Sent: Sunday, October 28, 2001 6:50 AM To: emc Subject: RE: skinny power cords. In North America we rate cordage according to usage. The probability of crushing a cord is dependent on its usage and the selection of the cordage type by the manufacturer. I have seen many IT manufacturers use SVT cordage in North America. In my opinion SVT cordage is chosen instead of SJT just to save money. SVT is for vacuum cleaners, not consumer products. So, would fusing a plug in the USA/Canada be needed? I say no because we have a working system to rate cordage according to usage. If people choose to abuse the system, they assume the risk and liability for doing so. Regards, +=+ |Ronald R. Wellman|Voice : 408-345-8229 | |Agilent Technologies |FAX : 408-553-2412 | |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| |Mailstop 54L-BB |WWW : http://www.agilent.com | |Santa Clara, California 95052 USA| | +=+ | "Common sense is the collection of prejudices acquired by age | | eighteen." - Albert Einstein | +=+ -Original Message- From: Nick Rouse [mailto:100626.3...@compuserve.com] Sent: Friday, October 26, 2001 2:11 PM To: emc Subject: Fw: skinny power cords. - Original Message - From: "Nick Rouse" <100626.3...@compuserve.com> To: "WELLMAN,RON (A-PaloAlto,ex1)" Sent: Friday, October 26, 2001 9:52 PM Subject: Re: skinny power cords. > Earlier on in the thread it was not about arcing across the pins of a plug > but about the dangers or having a power cord rated lower than the > protection in the supply. Damage to the cord such as squashing it under > the legs of furniture or repeated flexing or overloads in simple unfused > equipment like table lights can cause overheating in the cord that will not > trip out the circuit protection. > Fused plugs do allow thin power cords to be used safely from supplies that > have a high rated current, In the UK power outlets are on a ring protected > by a 30A or 50A fuse or breaker. > > Nick Rouse > > Original Message ----- > From: "WELLMAN,RON (A-PaloAlto,ex1)" > To: > Sent: Friday, October 26, 2001 3:05 PM > Subject: RE: skinny power cords.
Re: skinny power cords.
Ron, Thank you. I appreciate the reference to the NEC! taniagr...@msn.com - Original Message - From: acar...@uk.xyratex.com Sent: Monday, October 29, 2001 4:09 AM To: Tania Grant Cc: WELLMAN,RON (A-PaloAlto,ex1); emc Subject: Re: skinny power cords. Tania The V in SVT does indeed stand for Vacuum and not Vinyl. In reference to the Trade name of this type of cable being Vacuum cleaner cord not suitable for hard usage. Article 400 of the NEC, page 70-211 to 70-224 ( in the 1999 edition) defines all the US cordage definitions. What the letters mean and what use the cordage is suitable for. Tania Grant wrote: Ron, I am a bit confused;-- you stated " SVT is for vacuum cleaners, not consumer products."Is not a vacuum cleaner a consumer product??? I may be wrong, but I thought that the "V" in the SVT designation stands for "vinyl", a soft and flexible insulation. Since many vacuum cleaning cords are automatically wound inside the appliance, that suits the application quite well. SJT cords, on the other hand, are more stiff; however, they are also used with consumer products. Perhaps someone else can shed more specific light on the various U.S. power cord applications and their respective nomenclature. I know that in the SJTO designation, the "O" stands for resistance to Oil, and that such cords are recommended (required?) in industrial areas where oil would likely be present, such as in car garages, etc. Tania granttaniagr...@msn.com - Original Message - From: WELLMAN,RON (A-PaloAlto,ex1) Sent: Sunday, October 28, 2001 6:50 AM To: emc Subject: RE: skinny power cords. In North America we rate cordage according to usage. The probability of crushing a cord is dependent on its usage and the selection of the cordage type by the manufacturer. I have seen many IT manufacturers use SVT cordage in North America. In my opinion SVT cordage is chosen instead of SJT just to save money. SVT is for vacuum cleaners, not consumer products. So, would fusing a plug in the USA/Canada be needed? I say no because we have a working system to rate cordage according to usage. If people choose to abuse the system, they assume the risk and liability for doing so. Regards, +=+ |Ronald R. Wellman|Voice : 408-345-8229 | |Agilent Technologies |FAX : 408-553-2412 | |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| |Mailstop 54L-BB |WWW : http://www.agilent.com | |Santa Clara, California 95052 USA| | +=+ | "Common sense is the collection of prejudices acquired by age | | eighteen." - Albert Einstein | +=+ -Original Message- From: Nick Rouse [mailto:100626.3...@compuserve.com] Sent: Friday, October 26, 2001 2:11 PM To: emc Subject: Fw: skinny power cords. - Original Message - From: "Nick Rouse" <100626.3...@compuserve.com> To: "WELLMAN,RON (A-PaloAlto,ex1)" Sent: Friday, October 26, 2001 9:52 PM Subject: Re: skinny power cords. > Earlier on in the thread it was not about arcing across the pins of a plug > but about the dangers or having a power cord rated lower than the > protection in the supply. Damage to the cord such as squashing it under > the legs of furniture or repeated flexing or overloads in simple unfused > equipment like table lights can cause overheating in the cord that will not > trip out the circuit protection. > Fused plugs do allow thin power cords to be used safely from supplies that > have a high rated current, In the UK power outlets are on a ring protected > by a 30A or 50A fuse or breaker. > > Nick Rouse > > Original Message ----- > From: "WELLMAN,RON (A-PaloAlto,ex1)" > To: > Sent: Friday, October 26, 2001 3:05 PM > Subject: RE: skinny power cords. > > > > > > > > Hello all, > > > > Earlier on in this thread it was eluded that this problem was leading to > the > > need of fused power plugs, similar to what is done in the UK. However, > based > > on the analyses of several people, I do not see how a fused plug would of > > prevented the failure that Robert experienced. > > > > Regards, > > +=+ > > |Ronald R. Wellman|Voice : 408-345-8229 | > > |Agilent Technologies
Re: skinny power cords.
Tania The V in SVT does indeed stand for Vacuum and not Vinyl. In reference to the Trade name of this type of cable being Vacuum cleaner cord not suitable for hard usage. Article 400 of the NEC, page 70-211 to 70-224 ( in the 1999 edition) defines all the US cordage definitions. What the letters mean and what use the cordage is suitable for. Tania Grant wrote: > Ron, I am a bit confused;-- you stated " SVT is for vacuum cleaners, > not consumer products."Is not a vacuum cleaner a consumer product??? I > may be wrong, but I thought that the "V" in the SVT designation stands > for "vinyl", a soft and flexible insulation. Since many vacuum > cleaning cords are automatically wound inside the appliance, that > suits the application quite well. SJT cords, on the other hand, are > more stiff; however, they are also used with consumer > products. Perhaps someone else can shed more specific light on the > various U.S. power cord applications and their respective > nomenclature. I know that in the SJTO designation, the "O" stands > for resistance to Oil, and that such cords are recommended (required?) > in industrial areas where oil would likely be present, such as in car > garages, etc. Tania granttaniagr...@msn.com > > - Original Message - > From: WELLMAN,RON (A-PaloAlto,ex1) > Sent: Sunday, October 28, 2001 6:50 AM > To: emc > Subject: RE: skinny power cords. > > > > In North America we rate cordage according to usage. The > probability of > crushing a cord is dependent on its usage and the selection > of the cordage > type by the manufacturer. I have seen many IT manufacturers > use SVT cordage > in North America. In my opinion SVT cordage is chosen > instead of SJT just to > save money. SVT is for vacuum cleaners, not consumer > products. So, would > fusing a plug in the USA/Canada be needed? I say no because > we have a > working system to rate cordage according to usage. If people > choose to abuse > the system, they assume the risk and liability for doing so. > > Regards, > +=== > =+ > |Ronald R. Wellman|Voice : > 408-345-8229 | > |Agilent Technologies |FAX : > 408-553-2412 | > |5301 Stevens Creek Blvd.,|E-Mail: > ron_well...@agilent.com| > |Mailstop 54L-BB |WWW : > http://www.agilent.com | > |Santa Clara, California 95052 > USA| | > +=== > =+ > | "Common sense is the collection of prejudices acquired by > age | > | eighteen." - Albert > Einstein | > +=== > =+ > > > > -Original Message- > From: Nick Rouse [mailto:100626.3...@compuserve.com] > Sent: Friday, October 26, 2001 2:11 PM > To: emc > Subject: Fw: skinny power cords. > > > > > - Original Message - > From: "Nick Rouse" <100626.3...@compuserve.com> > To: "WELLMAN,RON (A-PaloAlto,ex1)" > > Sent: Friday, October 26, 2001 9:52 PM > Subject: Re: skinny power cords. > > > > Earlier on in the thread it was not about arcing across > the pins of a plug > > but about the dangers or having a power cord rated lower > than the > > protection in the supply. Damage to the cord such as > squashing it under > > the legs of furniture or repeated flexing or overloads in > simple unfused > > equipment like table lights can cause overheating in the > cord that will > not > > trip out the circuit protection. > > Fused plugs do allow thin power cords to be used safely > from supplies that > > have a high rated current, In the UK power outlets are on > a ring protected > > by a 30A or 50A fuse or breaker. > > > > Nick Rouse > > > > Original Message - > > From: "WELLMAN,RON (A-PaloAlto,ex1)" > > > To: > > Sent: Friday, October 26, 2001 3:05 PM > > Subject: RE: skinny power cords. > > > > > > > > > > > > > Hello all, > > > > > > Earlier on in this thread it was eluded that this > problem w
Re: skinny power cords.
I read in !emc-pstc that WELLMAN,RON (A-PaloAlto,ex1) wrote (in <999F6F1E8EB8D311AC190090277A7726086 58...@axcs08.cos.agilent.com>) about 'skinny power cords.', on Sun, 28 Oct 2001: >In the UK power outlets are on a ring protected >> by a 30A or 50A fuse or breaker. No, 30 A fuse or 32 A MCB. No 50 A. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Eat mink and be dreary! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Ron, I am a bit confused;-- you stated " SVT is for vacuum cleaners, not consumer products." Is not a vacuum cleaner a consumer product??? I may be wrong, but I thought that the "V" in the SVT designation stands for "vinyl", a soft and flexible insulation. Since many vacuum cleaning cords are automatically wound inside the appliance, that suits the application quite well. SJT cords, on the other hand, are more stiff; however, they are also used with consumer products. Perhaps someone else can shed more specific light on the various U.S. power cord applications and their respective nomenclature. I know that in the SJTO designation, the "O" stands for resistance to Oil, and that such cords are recommended (required?) in industrial areas where oil would likely be present, such as in car garages, etc. Tania Grant taniagr...@msn.com - Original Message - From: WELLMAN,RON (A-PaloAlto,ex1) Sent: Sunday, October 28, 2001 6:50 AM To: emc Subject: RE: skinny power cords. In North America we rate cordage according to usage. The probability of crushing a cord is dependent on its usage and the selection of the cordage type by the manufacturer. I have seen many IT manufacturers use SVT cordage in North America. In my opinion SVT cordage is chosen instead of SJT just to save money. SVT is for vacuum cleaners, not consumer products. So, would fusing a plug in the USA/Canada be needed? I say no because we have a working system to rate cordage according to usage. If people choose to abuse the system, they assume the risk and liability for doing so. Regards, +=+ |Ronald R. Wellman|Voice : 408-345-8229 | |Agilent Technologies |FAX : 408-553-2412 | |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| |Mailstop 54L-BB |WWW : http://www.agilent.com | |Santa Clara, California 95052 USA| | +=+ | "Common sense is the collection of prejudices acquired by age | | eighteen." - Albert Einstein | +=+ -Original Message- From: Nick Rouse [mailto:100626.3...@compuserve.com] Sent: Friday, October 26, 2001 2:11 PM To: emc Subject: Fw: skinny power cords. - Original Message - From: "Nick Rouse" <100626.3...@compuserve.com> To: "WELLMAN,RON (A-PaloAlto,ex1)" Sent: Friday, October 26, 2001 9:52 PM Subject: Re: skinny power cords. > Earlier on in the thread it was not about arcing across the pins of a plug > but about the dangers or having a power cord rated lower than the > protection in the supply. Damage to the cord such as squashing it under > the legs of furniture or repeated flexing or overloads in simple unfused > equipment like table lights can cause overheating in the cord that will not > trip out the circuit protection. > Fused plugs do allow thin power cords to be used safely from supplies that > have a high rated current, In the UK power outlets are on a ring protected > by a 30A or 50A fuse or breaker. > > Nick Rouse > > Original Message - > From: "WELLMAN,RON (A-PaloAlto,ex1)" > To: > Sent: Friday, October 26, 2001 3:05 PM > Subject: RE: skinny power cords. > > > > > > > > Hello all, > > > > Earlier on in this thread it was eluded that this problem was leading to > the > > need of fused power plugs, similar to what is done in the UK. However, > based > > on the analyses of several people, I do not see how a fused plug would of > > prevented the failure that Robert experienced. > > > > Regards, > > +=+ > > |Ronald R. Wellman|Voice : 408-345-8229 | > > |Agilent Technologies |FAX : 408-553-2412 | > > |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| > > |Mailstop 54L-BB |WWW : http://www.agilent.com | > > |Santa Clara, California 95052 USA| | > > +=+ > > | "Common sense is the collection of prejudices acquired by age | > > | eighteen." - Albert Einstein | > > +=+ > > > > --- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > Visit our web site at: http://www.ewh.i
RE: skinny power cords.
In North America we rate cordage according to usage. The probability of crushing a cord is dependent on its usage and the selection of the cordage type by the manufacturer. I have seen many IT manufacturers use SVT cordage in North America. In my opinion SVT cordage is chosen instead of SJT just to save money. SVT is for vacuum cleaners, not consumer products. So, would fusing a plug in the USA/Canada be needed? I say no because we have a working system to rate cordage according to usage. If people choose to abuse the system, they assume the risk and liability for doing so. Regards, +=+ |Ronald R. Wellman|Voice : 408-345-8229 | |Agilent Technologies |FAX : 408-553-2412 | |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| |Mailstop 54L-BB |WWW : http://www.agilent.com | |Santa Clara, California 95052 USA| | +=+ | "Common sense is the collection of prejudices acquired by age | | eighteen." - Albert Einstein | +=+ -Original Message- From: Nick Rouse [mailto:100626.3...@compuserve.com] Sent: Friday, October 26, 2001 2:11 PM To: emc Subject: Fw: skinny power cords. - Original Message - From: "Nick Rouse" <100626.3...@compuserve.com> To: "WELLMAN,RON (A-PaloAlto,ex1)" Sent: Friday, October 26, 2001 9:52 PM Subject: Re: skinny power cords. > Earlier on in the thread it was not about arcing across the pins of a plug > but about the dangers or having a power cord rated lower than the > protection in the supply. Damage to the cord such as squashing it under > the legs of furniture or repeated flexing or overloads in simple unfused > equipment like table lights can cause overheating in the cord that will not > trip out the circuit protection. > Fused plugs do allow thin power cords to be used safely from supplies that > have a high rated current, In the UK power outlets are on a ring protected > by a 30A or 50A fuse or breaker. > > Nick Rouse > > Original Message - > From: "WELLMAN,RON (A-PaloAlto,ex1)" > To: > Sent: Friday, October 26, 2001 3:05 PM > Subject: RE: skinny power cords. > > > > > > > > Hello all, > > > > Earlier on in this thread it was eluded that this problem was leading to > the > > need of fused power plugs, similar to what is done in the UK. However, > based > > on the analyses of several people, I do not see how a fused plug would of > > prevented the failure that Robert experienced. > > > > Regards, > > +=+ > > |Ronald R. Wellman|Voice : 408-345-8229 | > > |Agilent Technologies |FAX : 408-553-2412 | > > |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| > > |Mailstop 54L-BB |WWW : http://www.agilent.com | > > |Santa Clara, California 95052 USA| | > > +=+ > > | "Common sense is the collection of prejudices acquired by age | > > | eighteen." - Albert Einstein | > > +=+ > > > > --- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > > > To cancel your subscription, send mail to: > > majord...@ieee.org > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Michael Garretson:pstc_ad...@garretson.org > > Dave Healddavehe...@mediaone.net > > > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > > Jim Bacher: j.bac...@ieee.org > > > > All emc-pstc postings are archived and searchable on the web at: > > No longer online until our new server is brought online and the old > messages are imported into the new server. > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.o
Re: skinny power cords.
Robert Macy wrote >> Anyway, a little damn fuse in the plug would not have helped in this > circumstance, complete waste of time, much like the main breaker was. No the fuse in UK plugs would not have helped in this case but the 34mm of creepage distance between the pins that you get in most plugs built to of the latest version of BS1363 would most certainly have done so Nick Rouse --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
Robert Know that even UL Certified extension cords are for temporary use only. They are not to be plugged into an appliance and left undisturbed for a long period of time. Greg Nielsen Compliance Engineer Set Engineering, Inc. -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: Thursday, October 25, 2001 2:30 PM To: Jim Eichner; emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Yes, I believe it was contamination. There is a tissue box on the night stand above the outlet. Tissue lint is insidious. The extension cord had been plugged in (AND LEFT UNDISTURBED) for a long period of time. Exactly, how the buildup made its way to an inside surface I don't know. But remember, an experienced fireman related that this is how most electrical fires start in his experience - an outlet shorts between blades (or in that area), the breaker does not trip while the arc is sustained, flames develop, and great damage occurs. I was upset that the 15A breaker could care less about the arc sizzling at the outlet. The reason I mention the extension cord is to point out that the plug plugged into the outlet was high quality and not a "cheap" lamp cord of suspect origin. Yet, this plug still carbonized AND FLAMED! making things much worse. Now, I do maintenance around our home using compressed air can to blow the outlet box clear of everything and unplug everything and wipe all surfaces clean. This has worked, but may not always, since sprays etc used in the area tend to produce a gummy, waxlike deposit on the outlet and there still may be stuff down inside. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Jim Eichner To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 12:07 PM Subject: RE: skinny power cords. > >I'm curious: given that North American plug blades are >1/2" apart, there >must have been substantial contamination to aid in 120Vac jumping that far >(arcing). Did you identify any sort of contamination or moisture? > >Jim Eichner, P.Eng. >Manager, Engineering Services >Xantrex Technology Inc. >Mobile Power >phone: (604) 422-2546 >fax: (604) 420-1591 >e-mail: jim.eich...@xantrex.com >web: www.xantrex.com > > >-Original Message- >From: Robert Macy [mailto:m...@california.com] >Sent: Thursday, October 25, 2001 8:50 AM >To: Roman, Dan; emc-p...@majordomo.ieee.org >Subject: Re: skinny power cords. > > > >Just have to jump in here with personal experience: > >In our bedroom we have a deLonghi radiator heater which uses an extension >cord (high cost UL approved) heavy guage #12 wire to power it - when it's >used. This extension cord plugs into a "multi outlet" adapter, also heavy >duty UL approved. At the time of the incident there was no power being used >from this outlet. > >I was in another room, my wife was sitting on the edge of the bed watching a >news blurb on TV when she heard a funny sound, a scritch, scritch. She >called to me to come listen. Scritch, scritch, scritch got louder. As I >arrived, flames started lapping up the wall from the outlet while still >making arcing sounds. The flames were less than 6 inches from curtains. I >reached into all this and unplugged the extension cord which luckily stopped >the fireworks display. Imagine, if we had not been there. > >Upon examination, it appeared that an arc had formed between the blades of >the extension cord (remember no power at the time). That arc was not >sufficient to drop the 15A breaker to the outlet, yet was sufficient to >carbonize the UL approved material which further sustained the arc. > >I posted this to the newsgroup alt.home.repair where a fireman jumped in >describing how this exact mechanism is what starts most home fires! Isn't >that an encouraging thought! > >Anyway, a little damn fuse in the plug would not have helped in this >circumstance, complete waste of time, much like the main breaker was. > > - Robert - > > Robert A. Macy, PEm...@california.com > 408 286 3985 fx 408 297 9121 > AJM International Electronics Consultants > 619 North First St, San Jose, CA 95112 > >-Original Message- >From: Roman, Dan >To: emc-p...@majordomo.ieee.org >Date: Thursday, October 25, 2001 7:41 AM >Subject: RE: skinny power cords. > > >> >>I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >>in excess of 20A for
Re: skinny power cords.
I feel like jumping in on this very interesting and enlightening thread. As it reinforces a few issues I have often had to explain to the various design engineers and gives me more ammunition to support the need for fault testing. Just because a product is UL approved does not mean it is safe or suitable for the application. In Europe the LVD covers this quite clearly by stating that testing to a standard alone, is inadequate for demonstrating compliance to the directive. We have to go that one step further and consider forcible use and misuse. After all standards evolve as lessons, like this one, are learnt. If there were never any electrical fires, there would be no safety standards. When a new revision of a UL standard is issued, manufactures generally have 5 years before they must submit their old products for approval to the new level of standard. Even then, this does not apply to products already within the supply chain. The chap actually selling the goods might have no idea that the UL marked goods they are dutifully selling, were approved to a now defunct standard and they nolonger comply ! Also reinforces the basic rule, if it is plastic and the ignition source is large enough, it will burn. A 5V or V0 flame rating does not mean it is fire proof, just that it will not contribute to the fire. Personally though I have never been comfortable with US plugs and outlets with out an inbuilt on/off switch. I like our big chunky UK plugs. Anyway, slightly off track. But it Friday night, so time to say have a good weekend everyone. PS. Enough of the fish jokes ! Kenneth McCormick wrote: > I think the answer to the problem exists. The 2002 version of the National > Electric Code will require Arc Fault Interrupters in bedrooms. > > See the link below from the CPSC for details. > > http://www.cpsc.gov/cpscpub/pubs/afci.html > > >From: "Colgan, Chris" > >Reply-To: "Colgan, Chris" > >To: emc-p...@majordomo.ieee.org > >Subject: RE: skinny power cords. > >Date: Fri, 26 Oct 2001 09:51:20 +0100 > > > > > >I used to curse the size of our British BS1363 plugs and socket outlets. I > >won't be so hasty in the future. > > > >Chris Colgan > >Compliance Engineer > >TAG McLaren Audio Ltd > >The Summit, Latham Road > >Huntingdon, Cambs, PE29 6ZU > >*Tel: +44 (0)1480 415 627 > >*Fax: +44 (0)1480 52159 > >* Mailto:chris.col...@tagmclaren.com > >* http://www.tagmclaren.com > > > > > > > -Original Message- > > > From: Dan Kwok [SMTP:dk...@intetron.com] > > > Sent: 26 October 2001 00:10 > > > To: Robert Macy > > > Cc: emc-p...@majordomo.ieee.org > > > Subject:Re: skinny power cords. > > > > > > > > > Robert, > > > > > > It would seem this kind of problem may also happen without an extension > > > cord. I know a fellow that used to unplug most of his appliances from > > > the wall in anticipation of a lightning storm. I guess you can't be too > > > careful. > > > > > > - > > > Dan Kwok, P.Eng. > > > Principal Engineer > > > Electromagnetic Compatibility > > > Intetron Consulting, Inc. > > > Ph (604) 432-9874 > > > E-mail dk...@intetron.com > > > Internet http://www.intetron.com > > > > > > > > > > > > Robert Macy wrote: > > > > > > > > It definitely was not supplied by the heater company. It was a high > > > quality > > > > UL approved cord. It's just that this cord carbonized and burst into > > > flame > > > > as the arc was existing. The flames did immediately extinguish when > >the > > > arc > > > > was stopped by unplugging the cord which is good. > > > > > > > > But again, it was disturbing that the 15A breaker provided no > > > protection. > > > > > > > > Anyway, it was a good lesson for this "sleeping" guy. Now I take > > > electrical > > > > distribution inside my home much more seriously. > > > > > > > >- Robert - > > > > > > > >Robert A. Macy, PEm...@california.com > > > >408 286 3985 fx 408 297 9121 > > > >AJM International Electronics Consultants > > > >619 North First St, San Jose, CA 95112 > > > > > > > > -Original Message- > > > > From: Dan Kwok > > > > To: Robert Macy
RE: skinny power cords.
I think the answer to the problem exists. The 2002 version of the National Electric Code will require Arc Fault Interrupters in bedrooms. See the link below from the CPSC for details. http://www.cpsc.gov/cpscpub/pubs/afci.html From: "Colgan, Chris" Reply-To: "Colgan, Chris" To: emc-p...@majordomo.ieee.org Subject: RE: skinny power cords. Date: Fri, 26 Oct 2001 09:51:20 +0100 I used to curse the size of our British BS1363 plugs and socket outlets. I won't be so hasty in the future. Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:chris.col...@tagmclaren.com * http://www.tagmclaren.com > -Original Message- > From: Dan Kwok [SMTP:dk...@intetron.com] > Sent: 26 October 2001 00:10 > To:Robert Macy > Cc:emc-p...@majordomo.ieee.org > Subject: Re: skinny power cords. > > > Robert, > > It would seem this kind of problem may also happen without an extension > cord. I know a fellow that used to unplug most of his appliances from > the wall in anticipation of a lightning storm. I guess you can't be too > careful. > > - > Dan Kwok, P.Eng. > Principal Engineer > Electromagnetic Compatibility > Intetron Consulting, Inc. > Ph (604) 432-9874 > E-mail dk...@intetron.com > Internet http://www.intetron.com > > > > Robert Macy wrote: > > > > It definitely was not supplied by the heater company. It was a high > quality > > UL approved cord. It's just that this cord carbonized and burst into > flame > > as the arc was existing. The flames did immediately extinguish when the > arc > > was stopped by unplugging the cord which is good. > > > > But again, it was disturbing that the 15A breaker provided no > protection. > > > > Anyway, it was a good lesson for this "sleeping" guy. Now I take > electrical > > distribution inside my home much more seriously. > > > >- Robert - > > > >Robert A. Macy, PEm...@california.com > >408 286 3985 fx 408 297 9121 > >AJM International Electronics Consultants > >619 North First St, San Jose, CA 95112 > > > > -Original Message- > > From: Dan Kwok > > To: Robert Macy ; emc-p...@majordomo.ieee.org > > > > Date: Thursday, October 25, 2001 1:42 PM > > Subject: Re: skinny power cords. > > > > > > > >Hi Robert, > > > > > >Recently, I bought several similar heaters for my home. I recall > reading in > > >the operation instructions, explicit safety warnings against using > > extension > > >cords with the heater. Was the extension cord supplied with the heater? > > > > > > > > >- > > >Dan Kwok, P.Eng. > > >Principal Engineer > > >Electromagnetic Compatibility > > >Intetron Consulting, Inc. > > >Ph (604) 432-9874 > > >E-mail dk...@intetron.com > > >Internet http://www.intetron.com > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. ** Please visit us at www.tagmclaren.com ** The contents of this E-mail are confidential and for the exclusive use of the intended recipient. If you receive this E-mail in error, please delete it from your system immediately and notify us either by E-mail, telephone or fax. You should not copy, forward or otherwise disclose the content of the E-mail. TAG McLaren Audio Ltd The Summit, 11 Latham Road Huntingdon, Cambs, PE29 6ZU Telephone : 01480 415600 (
RE: skinny power cords.
Hello all, Earlier on in this thread it was eluded that this problem was leading to the need of fused power plugs, similar to what is done in the UK. However, based on the analyses of several people, I do not see how a fused plug would of prevented the failure that Robert experienced. Regards, +=+ |Ronald R. Wellman|Voice : 408-345-8229 | |Agilent Technologies |FAX : 408-553-2412 | |5301 Stevens Creek Blvd.,|E-Mail: ron_well...@agilent.com| |Mailstop 54L-BB |WWW : http://www.agilent.com | |Santa Clara, California 95052 USA| | +=+ | "Common sense is the collection of prejudices acquired by age | | eighteen." - Albert Einstein | +=+ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
I used to curse the size of our British BS1363 plugs and socket outlets. I won't be so hasty in the future. Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:chris.col...@tagmclaren.com * http://www.tagmclaren.com > -Original Message- > From: Dan Kwok [SMTP:dk...@intetron.com] > Sent: 26 October 2001 00:10 > To: Robert Macy > Cc: emc-p...@majordomo.ieee.org > Subject: Re: skinny power cords. > > > Robert, > > It would seem this kind of problem may also happen without an extension > cord. I know a fellow that used to unplug most of his appliances from > the wall in anticipation of a lightning storm. I guess you can't be too > careful. > > - > Dan Kwok, P.Eng. > Principal Engineer > Electromagnetic Compatibility > Intetron Consulting, Inc. > Ph (604) 432-9874 > E-mail dk...@intetron.com > Internet http://www.intetron.com > > > > Robert Macy wrote: > > > > It definitely was not supplied by the heater company. It was a high > quality > > UL approved cord. It's just that this cord carbonized and burst into > flame > > as the arc was existing. The flames did immediately extinguish when the > arc > > was stopped by unplugging the cord which is good. > > > > But again, it was disturbing that the 15A breaker provided no > protection. > > > > Anyway, it was a good lesson for this "sleeping" guy. Now I take > electrical > > distribution inside my home much more seriously. > > > >- Robert - > > > >Robert A. Macy, PEm...@california.com > >408 286 3985 fx 408 297 9121 > >AJM International Electronics Consultants > > 619 North First St, San Jose, CA 95112 > > > > -Original Message- > > From: Dan Kwok > > To: Robert Macy ; emc-p...@majordomo.ieee.org > > > > Date: Thursday, October 25, 2001 1:42 PM > > Subject: Re: skinny power cords. > > > > > > > >Hi Robert, > > > > > >Recently, I bought several similar heaters for my home. I recall > reading in > > >the operation instructions, explicit safety warnings against using > > extension > > >cords with the heater. Was the extension cord supplied with the heater? > > > > > > > > >- > > >Dan Kwok, P.Eng. > > >Principal Engineer > > >Electromagnetic Compatibility > > >Intetron Consulting, Inc. > > >Ph (604) 432-9874 > > >E-mail dk...@intetron.com > > >Internet http://www.intetron.com > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. ** Please visit us at www.tagmclaren.com ** The contents of this E-mail are confidential and for the exclusive use of the intended recipient. If you receive this E-mail in error, please delete it from your system immediately and notify us either by E-mail, telephone or fax. You should not copy, forward or otherwise disclose the content of the E-mail. TAG McLaren Audio Ltd The Summit, 11 Latham Road Huntingdon, Cambs, PE29 6ZU Telephone : 01480 415600 (+44 1480 415600) Facsimile : 01480 52159 (+44 1480 52159) ** Please visit us at www.tagmclaren.com ** --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at
RE: skinny power cords.
"Far be it from me to criticize" UL Listed products, or UL standards, but it seems to me that the plug in question was not "suitable for its intended use". I can recall conducting a humidity test on one of our products, and at the conclusion of the test, it failed a dielectric test, and I traced the failure to a UL Listed or Recognized plug, where the insulating material which carried the pins appeared to be little more than layers of compressed paper !! Regards, John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: 25 October 2001 22:11 To: jack.c...@cax.usa.xerox.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jack: > I'm having a problem with Rich's explanation in this particular case (I know > it's often true, though). How did resisitive heating occur *without* > current flow? It was clearly stated that the heater was switched OFF. I believe that the process I described takes a lot of time. It starts when the heater is first used, i.e., a heavy current through the plug and socket. The heating due to the contact resistance degrades the material between the blades of the plug due to pyrolysis, the decomposition of a material by heat alone. The decomposition results in unknown materials between the blades. Plastics are carbon-based. Decomposition of carbon-based materials tends to reduce the size of the molecule, and the material approaches pure carbon, a resistor. So, we can assume that these unknown materials are resistive. We will have a leakage current through the resistance. Once the leakage path is established, the heater does not need to be on for the process to continue. Since this isn't a "good" resistance, some elements will open, and micro-arcs will occur. These micro- arcs create new resistances, and the leakage current will continue to increase. And the arcs get bigger. Etc. I could be wrong... Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
This subject of reliance on branch circuit protection for loads has been discussed for a long time and involves a lot of historical tradition and code and standards activities. The following is my understanding based on some code committee activities, but I have not researched this historically. You will generally find two kinds of faults which need protection, overloads and short circuits. Overloads are generally faults in an operating product which provide moderate increases in the load. Short circuits may occur between supply conductors or to ground and involve very high currents. The branch circuit protection provides overload and short protection for the branch circuit wiring. The overcurrent is sized to prevent overheating of any branch circuit wiring on either a low current long term or high current short term basis. In some cases you will find breakers which have inductive trip for shorts and thermal trip for overloads. Appliances and the associated cords are expected to be protected by product design. Traditionally we have been able to rely on the branch protection for shorts (which are high current and should trip the branch overcurrent protection). For overloads, internal protection is provided such as additional smaller overcurrent protection, impedance protection, fault testing, etc. In the US the traditional sizing means a cord as small as 18 AWG could be used, since it would usually trip a 15 or 20 amp circuit when shorted. An exception was shaver (tinsel) cords which typically opened under fault and were attended. As has been mentioned in this thread, these basic ideas did not always work as planned. For example, loose connections will often overheat connectors, carbonizing the plastics and resulting in a resistive heat which over time ignites. Short circuits are often high impedance, either because few wire strands are involved or because an arc is involved. Extension cords were overloaded. It turns out circuit breaker curves sometimes permitted an arc to melt the copper and blow the circuit open, sometimes repeatedly, without tripping. Fuses were much more responsive in this case. Gradual improvements have been seen in codes and standards. For example, smaller gauge extension cords and outlet strips now have overcurrent protection. Arc fault breakers have been introduced to detect and open wiring shorts. Breaker curves have been readjusted. Recent code cycles have considered introducing plug located overcurrent as Britain has done. Ground fault interrupters have also played a part in reducing ignition faults. Experience with these improvements will be considered as future code and standard changes are proposed. Bob Johnson --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Scott, Defective cords have been around long before someone got the idea to manufacture them offshore. How would you be able to tell, without using the "Hershey" criteria, if a power cord is any good? Dan Kwok Scott Lacey wrote: > > Jim, > It seems that some of the "offshore" manufactured cords are molded from > melted Hershey bars! I am always very careful who I buy my cords from. > > Scott Lacey > > -Original Message- > From: owner-emc-p...@majordomo.ieee.org > [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Jim Eichner > Sent: Thursday, October 25, 2001 3:40 PM > Cc: emc-p...@majordomo.ieee.org > Subject: RE: skinny power cords. > > Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the > tracking index tests are meant to address? I thought that any UL-approved > wiring device like this would have a material that is designed to resist > tracking, hence my speculation that contamination might be involved. > > I guess there are a few more comments to be made here... > > 1. From what I know, the tracking index tests are horribly non-repeatable > and are therefore somewhat meaningless. > > 2. The standards for plug caps and for multi-taps may not refer to UL746 and > may not have any of their own requirements for tracking index of insulation. > > 3. We could take this as evidence that even compliance with the tracking > index requirements doesn't prevent carbonization of the material where > there's a high temperature heat source involved. > > There are lots of people who unplug anything they are not actively using. I > guess it's not such a paranoid practice! > > Regards, > Jim Eichner, P.Eng. > Manager, Engineering Services > Xantrex Technology Inc. > Mobile Power > web: www.xantrex.com <http://www.xantrex.com> > Any opinions expressed are those of my invisible friend, who really > exists. Honest. > > -Original Message----- > From: Rich Nute [mailto:ri...@sdd.hp.com] > Sent: Thursday, October 25, 2001 12:14 PM > To: jim.eich...@xantrex.com > Cc: emc-p...@majordomo.ieee.org > Subject: Re: skinny power cords. > > Hi Jim: > > > I'm curious: given that North American plug blades are >1/2" apart, > there > > must have been substantial contamination to aid in 120Vac jumping that > far > > (arcing). Did you identify any sort of contamination or moisture? > > I don't believe contamination is a significant factor > in events such as this one. > > I believe such events start with a loose connection > between the plug and the socket (or between the wire > and the socket parts). A loose connection means > that the contact area is relatively small. In turn, > this means high current density at the point of > contact. > > The smaller the contact area, the greater the > resistance of the contact. > > The smaller the contact area, the greater the current > density at the point of contact. > > These two factors contribute to heating of the two > parts, the plug blade and the socket. Heating tends > to reduce the "springiness" of the socket part, and > of the connection between the supply wire and the > socket (because they are thermally connected). > > The heating also tends to degrade the surface of the > insulating material in which the conductors are mounted. > > Heating also enhances oxidation of the plating on the > parts, which further increases the resistance of the > connections. > > If the plug-connected appliance is "ON," arcing can > occur as the parts expand due to heating and make > various intermittant connections. Arc temperatures > are very high, and can "burn" the surface of nearby > insulating materials via radiation. > > As the surface degrades, leakages occur across the > surfaces. At this point, whether or not the appliance > is on or even connected is not a factor. There is a > current path between the two poles along the surface > of the insulator. This can either be between the > socket parts, or between the wired parts. The leakage > current causes further heating and micro-arcs where > the leakage path opens due to current density. The > micro-arcs further damage the insulator until there > is nearly continuous micro-arcing. I suggest this > is the source of the noise. The heat from the micro- > arcing and the resistance of the carbonized surface > of the insulator eventually lead to ignition and > flames. > > I admit that this is a hypothesis. I believe that > the process is more-or-less correct, but the details > may not be correct. > > Best regards, >
Re: skinny power cords.
Robert, It would seem this kind of problem may also happen without an extension cord. I know a fellow that used to unplug most of his appliances from the wall in anticipation of a lightning storm. I guess you can't be too careful. - Dan Kwok, P.Eng. Principal Engineer Electromagnetic Compatibility Intetron Consulting, Inc. Ph (604) 432-9874 E-mail dk...@intetron.com Internet http://www.intetron.com Robert Macy wrote: > > It definitely was not supplied by the heater company. It was a high quality > UL approved cord. It's just that this cord carbonized and burst into flame > as the arc was existing. The flames did immediately extinguish when the arc > was stopped by unplugging the cord which is good. > > But again, it was disturbing that the 15A breaker provided no protection. > > Anyway, it was a good lesson for this "sleeping" guy. Now I take electrical > distribution inside my home much more seriously. > >- Robert - > >Robert A. Macy, PEm...@california.com >408 286 3985 fx 408 297 9121 >AJM International Electronics Consultants >619 North First St, San Jose, CA 95112 > > -Original Message- > From: Dan Kwok > To: Robert Macy ; emc-p...@majordomo.ieee.org > > Date: Thursday, October 25, 2001 1:42 PM > Subject: Re: skinny power cords. > > > > >Hi Robert, > > > >Recently, I bought several similar heaters for my home. I recall reading in > >the operation instructions, explicit safety warnings against using > extension > >cords with the heater. Was the extension cord supplied with the heater? > > > > > >- > >Dan Kwok, P.Eng. > >Principal Engineer > >Electromagnetic Compatibility > >Intetron Consulting, Inc. > >Ph (604) 432-9874 > >E-mail dk...@intetron.com > >Internet http://www.intetron.com > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
Jim, It seems that some of the "offshore" manufactured cords are molded from melted Hershey bars! I am always very careful who I buy my cords from. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Jim Eichner Sent: Thursday, October 25, 2001 3:40 PM Cc: emc-p...@majordomo.ieee.org Subject: RE: skinny power cords. Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the tracking index tests are meant to address? I thought that any UL-approved wiring device like this would have a material that is designed to resist tracking, hence my speculation that contamination might be involved. I guess there are a few more comments to be made here... 1. From what I know, the tracking index tests are horribly non-repeatable and are therefore somewhat meaningless. 2. The standards for plug caps and for multi-taps may not refer to UL746 and may not have any of their own requirements for tracking index of insulation. 3. We could take this as evidence that even compliance with the tracking index requirements doesn't prevent carbonization of the material where there's a high temperature heat source involved. There are lots of people who unplug anything they are not actively using. I guess it's not such a paranoid practice! Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com <http://www.xantrex.com> Any opinions expressed are those of my invisible friend, who really exists. Honest. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 12:14 PM To: jim.eich...@xantrex.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jim: > I'm curious: given that North American plug blades are >1/2" apart, there > must have been substantial contamination to aid in 120Vac jumping that far > (arcing). Did you identify any sort of contamination or moisture? I don't believe contamination is a significant factor in events such as this one. I believe such events start with a loose connection between the plug and the socket (or between the wire and the socket parts). A loose connection means that the contact area is relatively small. In turn, this means high current density at the point of contact. The smaller the contact area, the greater the resistance of the contact. The smaller the contact area, the greater the current density at the point of contact. These two factors contribute to heating of the two parts, the plug blade and the socket. Heating tends to reduce the "springiness" of the socket part, and of the connection between the supply wire and the socket (because they are thermally connected). The heating also tends to degrade the surface of the insulating material in which the conductors are mounted. Heating also enhances oxidation of the plating on the parts, which further increases the resistance of the connections. If the plug-connected appliance is "ON," arcing can occur as the parts expand due to heating and make various intermittant connections. Arc temperatures are very high, and can "burn" the surface of nearby insulating materials via radiation. As the surface degrades, leakages occur across the surfaces. At this point, whether or not the appliance is on or even connected is not a factor. There is a current path between the two poles along the surface of the insulator. This can either be between the socket parts, or between the wired parts. The leakage current causes further heating and micro-arcs where the leakage path opens due to current density. The micro-arcs further damage the insulator until there is nearly continuous micro-arcing. I suggest this is the source of the noise. The heat from the micro- arcing and the resistance of the carbonized surface of the insulator eventually lead to ignition and flames. I admit that this is a hypothesis. I believe that the process is more-or-less correct, but the details may not be correct. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --
Re: skinny power cords.
Yes, This the reason that the arc fault interrupter was invented. New codes require it on bedroom circuits I understand. Regards, Lee Schmitz --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
It definitely was not supplied by the heater company. It was a high quality UL approved cord. It's just that this cord carbonized and burst into flame as the arc was existing. The flames did immediately extinguish when the arc was stopped by unplugging the cord which is good. But again, it was disturbing that the 15A breaker provided no protection. Anyway, it was a good lesson for this "sleeping" guy. Now I take electrical distribution inside my home much more seriously. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Dan Kwok To: Robert Macy ; emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 1:42 PM Subject: Re: skinny power cords. > >Hi Robert, > >Recently, I bought several similar heaters for my home. I recall reading in >the operation instructions, explicit safety warnings against using extension >cords with the heater. Was the extension cord supplied with the heater? > > >- >Dan Kwok, P.Eng. >Principal Engineer >Electromagnetic Compatibility >Intetron Consulting, Inc. >Ph (604) 432-9874 >E-mail dk...@intetron.com >Internet http://www.intetron.com > >- Original Message - >From: "Robert Macy" >To: "Roman, Dan" ; >Sent: Thursday, October 25, 2001 8:49 AM >Subject: Re: skinny power cords. > > >> >> Just have to jump in here with personal experience: >> >> In our bedroom we have a deLonghi radiator heater which uses an extension >> cord (high cost UL approved) heavy guage #12 wire to power it - when it's >> used. This extension cord plugs into a "multi outlet" adapter, also heavy >> duty UL approved. At the time of the incident there was no power being >used >> from this outlet. >> >> I was in another room, my wife was sitting on the edge of the bed watching >a >> news blurb on TV when she heard a funny sound, a scritch, scritch. She >> called to me to come listen. Scritch, scritch, scritch got louder. As I >> arrived, flames started lapping up the wall from the outlet while still >> making arcing sounds. The flames were less than 6 inches from curtains. I >> reached into all this and unplugged the extension cord which luckily >stopped >> the fireworks display. Imagine, if we had not been there. >> >> Upon examination, it appeared that an arc had formed between the blades of >> the extension cord (remember no power at the time). That arc was not >> sufficient to drop the 15A breaker to the outlet, yet was sufficient to >> carbonize the UL approved material which further sustained the arc. >> >> I posted this to the newsgroup alt.home.repair where a fireman jumped in >> describing how this exact mechanism is what starts most home fires! Isn't >> that an encouraging thought! >> >> Anyway, a little damn fuse in the plug would not have helped in this >> circumstance, complete waste of time, much like the main breaker was. >> >> - Robert - >> >>Robert A. Macy, PE m...@california.com >>408 286 3985 fx 408 297 9121 >>AJM International Electronics Consultants >>619 North First St, San Jose, CA 95112 >> >> -Original Message- >> From: Roman, Dan >> To: emc-p...@majordomo.ieee.org >> Date: Thursday, October 25, 2001 7:41 AM >> Subject: RE: skinny power cords. >> >> >> > >> >I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >> >in excess of 20A for a short period of time without starting to smoke >> (heck, >> >it'll handle close to in excess of 60A for a very very short time without >> >bursting into flames--not that it was a good experience finding this out). >> >Point is, the cordage will handle a fault either indefinitely or long >> enough >> >for the branch circuit breaker to trip provided you are connected to a 15A >> >or 20A branch circuit. >> > >> >Another data point, you routinely pass more current through the cord when >> >doing the earthing test and that uses more current than the cord is rated. >> >Leave the tester on for awhile and the cord does not really heat up >either. >> > >> >What this list needs is a power cord manufacturer or agency safety >engineer >> >that d
Re: skinny power cords.
Yes, I believe it was contamination. There is a tissue box on the night stand above the outlet. Tissue lint is insidious. The extension cord had been plugged in (AND LEFT UNDISTURBED) for a long period of time. Exactly, how the buildup made its way to an inside surface I don't know. But remember, an experienced fireman related that this is how most electrical fires start in his experience - an outlet shorts between blades (or in that area), the breaker does not trip while the arc is sustained, flames develop, and great damage occurs. I was upset that the 15A breaker could care less about the arc sizzling at the outlet. The reason I mention the extension cord is to point out that the plug plugged into the outlet was high quality and not a "cheap" lamp cord of suspect origin. Yet, this plug still carbonized AND FLAMED! making things much worse. Now, I do maintenance around our home using compressed air can to blow the outlet box clear of everything and unplug everything and wipe all surfaces clean. This has worked, but may not always, since sprays etc used in the area tend to produce a gummy, waxlike deposit on the outlet and there still may be stuff down inside. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Jim Eichner To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 12:07 PM Subject: RE: skinny power cords. > >I'm curious: given that North American plug blades are >1/2" apart, there >must have been substantial contamination to aid in 120Vac jumping that far >(arcing). Did you identify any sort of contamination or moisture? > >Jim Eichner, P.Eng. >Manager, Engineering Services >Xantrex Technology Inc. >Mobile Power >phone: (604) 422-2546 >fax: (604) 420-1591 >e-mail: jim.eich...@xantrex.com >web: www.xantrex.com > > >-Original Message- >From: Robert Macy [mailto:m...@california.com] >Sent: Thursday, October 25, 2001 8:50 AM >To: Roman, Dan; emc-p...@majordomo.ieee.org >Subject: Re: skinny power cords. > > > >Just have to jump in here with personal experience: > >In our bedroom we have a deLonghi radiator heater which uses an extension >cord (high cost UL approved) heavy guage #12 wire to power it - when it's >used. This extension cord plugs into a "multi outlet" adapter, also heavy >duty UL approved. At the time of the incident there was no power being used >from this outlet. > >I was in another room, my wife was sitting on the edge of the bed watching a >news blurb on TV when she heard a funny sound, a scritch, scritch. She >called to me to come listen. Scritch, scritch, scritch got louder. As I >arrived, flames started lapping up the wall from the outlet while still >making arcing sounds. The flames were less than 6 inches from curtains. I >reached into all this and unplugged the extension cord which luckily stopped >the fireworks display. Imagine, if we had not been there. > >Upon examination, it appeared that an arc had formed between the blades of >the extension cord (remember no power at the time). That arc was not >sufficient to drop the 15A breaker to the outlet, yet was sufficient to >carbonize the UL approved material which further sustained the arc. > >I posted this to the newsgroup alt.home.repair where a fireman jumped in >describing how this exact mechanism is what starts most home fires! Isn't >that an encouraging thought! > >Anyway, a little damn fuse in the plug would not have helped in this >circumstance, complete waste of time, much like the main breaker was. > > - Robert - > > Robert A. Macy, PEm...@california.com > 408 286 3985 fx 408 297 9121 > AJM International Electronics Consultants > 619 North First St, San Jose, CA 95112 > >-Original Message- >From: Roman, Dan >To: emc-p...@majordomo.ieee.org >Date: Thursday, October 25, 2001 7:41 AM >Subject: RE: skinny power cords. > > >> >>I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >>in excess of 20A for a short period of time without starting to smoke >(heck, >>it'll handle close to in excess of 60A for a very very short time without >>bursting into flames--not that it was a good experience finding this out). >>Point is, the cordage will handle a fault either indefinitely or long >enough >>for the branch circuit breaker to trip provided you are connected to a 15A >>or 20A branch circu
RE: skinny power cords.
Rich, Ok. That makes sense. Thanks for the follow-up. This is scary stuff! Jack Cook Xerox EMC Engineering -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 2:11 PM To: jack.c...@cax.usa.xerox.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jack: > I'm having a problem with Rich's explanation in this particular case (I know > it's often true, though). How did resisitive heating occur *without* > current flow? It was clearly stated that the heater was switched OFF. I believe that the process I described takes a lot of time. It starts when the heater is first used, i.e., a heavy current through the plug and socket. The heating due to the contact resistance degrades the material between the blades of the plug due to pyrolysis, the decomposition of a material by heat alone. The decomposition results in unknown materials between the blades. Plastics are carbon-based. Decomposition of carbon-based materials tends to reduce the size of the molecule, and the material approaches pure carbon, a resistor. So, we can assume that these unknown materials are resistive. We will have a leakage current through the resistance. Once the leakage path is established, the heater does not need to be on for the process to continue. Since this isn't a "good" resistance, some elements will open, and micro-arcs will occur. These micro- arcs create new resistances, and the leakage current will continue to increase. And the arcs get bigger. Etc. I could be wrong... Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Hi Jack: > I'm having a problem with Rich's explanation in this particular case (I know > it's often true, though). How did resisitive heating occur *without* > current flow? It was clearly stated that the heater was switched OFF. I believe that the process I described takes a lot of time. It starts when the heater is first used, i.e., a heavy current through the plug and socket. The heating due to the contact resistance degrades the material between the blades of the plug due to pyrolysis, the decomposition of a material by heat alone. The decomposition results in unknown materials between the blades. Plastics are carbon-based. Decomposition of carbon-based materials tends to reduce the size of the molecule, and the material approaches pure carbon, a resistor. So, we can assume that these unknown materials are resistive. We will have a leakage current through the resistance. Once the leakage path is established, the heater does not need to be on for the process to continue. Since this isn't a "good" resistance, some elements will open, and micro-arcs will occur. These micro- arcs create new resistances, and the leakage current will continue to increase. And the arcs get bigger. Etc. I could be wrong... Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
Got it - thanks for the explanation. Jim -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 1:58 PM To: jim.eich...@xantrex.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jim: > Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the > tracking index tests are meant to address? I thought that any UL-approved > wiring device like this would have a material that is designed to resist > tracking, hence my speculation that contamination might be involved. No, I believe the UL tracking index tests do not address the scenario I described. My scenario starts with heating the insulating material to the point where it begins to pyrolyze, i.e., decompose by heat alone. The UL tracking index test starts with a drop of saline solution to provide a resistive path on the surface of the plastic insulator. The micro-arcs occur in the saline solution. In my scenario, pyrolysis, not pollution, leads to the micro-arcs. So, I don't believe the tracking index is necessarily a predictor of tracking due to pyrolysis. I could be wrong... Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Hi Jim: > Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the > tracking index tests are meant to address? I thought that any UL-approved > wiring device like this would have a material that is designed to resist > tracking, hence my speculation that contamination might be involved. No, I believe the UL tracking index tests do not address the scenario I described. My scenario starts with heating the insulating material to the point where it begins to pyrolyze, i.e., decompose by heat alone. The UL tracking index test starts with a drop of saline solution to provide a resistive path on the surface of the plastic insulator. The micro-arcs occur in the saline solution. In my scenario, pyrolysis, not pollution, leads to the micro-arcs. So, I don't believe the tracking index is necessarily a predictor of tracking due to pyrolysis. I could be wrong... Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
Don't really have time for this, but ... I'm having a problem with Rich's explanation in this particular case (I know it's often true, though). How did resisitive heating occur *without* current flow? It was clearly stated that the heater was switched OFF. But then striking an arc between the flat blades is hard to explain also. An in-plug fuse would not have helped in that case. //Jack -Original Message- From: Jim Eichner [mailto:jim.eich...@xantrex.com] Sent: Thursday, October 25, 2001 12:40 PM Cc: emc-p...@majordomo.ieee.org Subject: RE: skinny power cords. Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the tracking index tests are meant to address? I thought that any UL-approved wiring device like this would have a material that is designed to resist tracking, hence my speculation that contamination might be involved. I guess there are a few more comments to be made here... 1. From what I know, the tracking index tests are horribly non-repeatable and are therefore somewhat meaningless. 2. The standards for plug caps and for multi-taps may not refer to UL746 and may not have any of their own requirements for tracking index of insulation. 3. We could take this as evidence that even compliance with the tracking index requirements doesn't prevent carbonization of the material where there's a high temperature heat source involved. There are lots of people who unplug anything they are not actively using. I guess it's not such a paranoid practice! Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com <http://www.xantrex.com> Any opinions expressed are those of my invisible friend, who really exists. Honest. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 12:14 PM To: jim.eich...@xantrex.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jim: > I'm curious: given that North American plug blades are >1/2" apart, there > must have been substantial contamination to aid in 120Vac jumping that far > (arcing). Did you identify any sort of contamination or moisture? I don't believe contamination is a significant factor in events such as this one. I believe such events start with a loose connection between the plug and the socket (or between the wire and the socket parts). A loose connection means that the contact area is relatively small. In turn, this means high current density at the point of contact. The smaller the contact area, the greater the resistance of the contact. The smaller the contact area, the greater the current density at the point of contact. These two factors contribute to heating of the two parts, the plug blade and the socket. Heating tends to reduce the "springiness" of the socket part, and of the connection between the supply wire and the socket (because they are thermally connected). The heating also tends to degrade the surface of the insulating material in which the conductors are mounted. Heating also enhances oxidation of the plating on the parts, which further increases the resistance of the connections. If the plug-connected appliance is "ON," arcing can occur as the parts expand due to heating and make various intermittant connections. Arc temperatures are very high, and can "burn" the surface of nearby insulating materials via radiation. As the surface degrades, leakages occur across the surfaces. At this point, whether or not the appliance is on or even connected is not a factor. There is a current path between the two poles along the surface of the insulator. This can either be between the socket parts, or between the wired parts. The leakage current causes further heating and micro-arcs where the leakage path opens due to current density. The micro-arcs further damage the insulator until there is nearly continuous micro-arcing. I suggest this is the source of the noise. The heat from the micro- arcing and the resistance of the carbonized surface of the insulator eventually lead to ignition and flames. I admit that this is a hypothesis. I believe that the process is more-or-less correct, but the details may not be correct. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher:
Re: skinny power cords.
Hi Robert, Recently, I bought several similar heaters for my home. I recall reading in the operation instructions, explicit safety warnings against using extension cords with the heater. Was the extension cord supplied with the heater? - Dan Kwok, P.Eng. Principal Engineer Electromagnetic Compatibility Intetron Consulting, Inc. Ph (604) 432-9874 E-mail dk...@intetron.com Internet http://www.intetron.com - Original Message - From: "Robert Macy" To: "Roman, Dan" ; Sent: Thursday, October 25, 2001 8:49 AM Subject: Re: skinny power cords. > > Just have to jump in here with personal experience: > > In our bedroom we have a deLonghi radiator heater which uses an extension > cord (high cost UL approved) heavy guage #12 wire to power it - when it's > used. This extension cord plugs into a "multi outlet" adapter, also heavy > duty UL approved. At the time of the incident there was no power being used > from this outlet. > > I was in another room, my wife was sitting on the edge of the bed watching a > news blurb on TV when she heard a funny sound, a scritch, scritch. She > called to me to come listen. Scritch, scritch, scritch got louder. As I > arrived, flames started lapping up the wall from the outlet while still > making arcing sounds. The flames were less than 6 inches from curtains. I > reached into all this and unplugged the extension cord which luckily stopped > the fireworks display. Imagine, if we had not been there. > > Upon examination, it appeared that an arc had formed between the blades of > the extension cord (remember no power at the time). That arc was not > sufficient to drop the 15A breaker to the outlet, yet was sufficient to > carbonize the UL approved material which further sustained the arc. > > I posted this to the newsgroup alt.home.repair where a fireman jumped in > describing how this exact mechanism is what starts most home fires! Isn't > that an encouraging thought! > > Anyway, a little damn fuse in the plug would not have helped in this > circumstance, complete waste of time, much like the main breaker was. > > - Robert - > >Robert A. Macy, PEm...@california.com >408 286 3985 fx 408 297 9121 >AJM International Electronics Consultants >619 North First St, San Jose, CA 95112 > > -----Original Message- > From: Roman, Dan > To: emc-p...@majordomo.ieee.org > Date: Thursday, October 25, 2001 7:41 AM > Subject: RE: skinny power cords. > > > > > >I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well > >in excess of 20A for a short period of time without starting to smoke > (heck, > >it'll handle close to in excess of 60A for a very very short time without > >bursting into flames--not that it was a good experience finding this out). > >Point is, the cordage will handle a fault either indefinitely or long > enough > >for the branch circuit breaker to trip provided you are connected to a 15A > >or 20A branch circuit. > > > >Another data point, you routinely pass more current through the cord when > >doing the earthing test and that uses more current than the cord is rated. > >Leave the tester on for awhile and the cord does not really heat up either. > > > >What this list needs is a power cord manufacturer or agency safety engineer > >that does power cords to settle this once and for all! > > > >Dan > > > >-Original Message- > >From: Scott Lacey [mailto:sco...@world.std.com] > >Sent: Wednesday, October 24, 2001 7:43 PM > >To: Gary McInturff > >Cc: emc-p...@majordomo.ieee.org > >Subject: RE: skinny power cords. > > > > > > > >Gary, > >I believe the answer is that the power cord rating of 6 or 10 amps is the > >operating current, at which it will have minimum temperature rise. Under > >fault conditions it will experience a rather dramatic temperature rise that > >is still well below the melting temperature of the insulation. The breaker > >or fuse should clear well before the cord is "cooked" to the point of > >failure. > > > >Scott Lacey > > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to t
RE: skinny power cords.
Thanks Rich: I suspect you're right. Isn't that mechanism exactly what the tracking index tests are meant to address? I thought that any UL-approved wiring device like this would have a material that is designed to resist tracking, hence my speculation that contamination might be involved. I guess there are a few more comments to be made here... 1. From what I know, the tracking index tests are horribly non-repeatable and are therefore somewhat meaningless. 2. The standards for plug caps and for multi-taps may not refer to UL746 and may not have any of their own requirements for tracking index of insulation. 3. We could take this as evidence that even compliance with the tracking index requirements doesn't prevent carbonization of the material where there's a high temperature heat source involved. There are lots of people who unplug anything they are not actively using. I guess it's not such a paranoid practice! Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com <http://www.xantrex.com> Any opinions expressed are those of my invisible friend, who really exists. Honest. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Thursday, October 25, 2001 12:14 PM To: jim.eich...@xantrex.com Cc: emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Hi Jim: > I'm curious: given that North American plug blades are >1/2" apart, there > must have been substantial contamination to aid in 120Vac jumping that far > (arcing). Did you identify any sort of contamination or moisture? I don't believe contamination is a significant factor in events such as this one. I believe such events start with a loose connection between the plug and the socket (or between the wire and the socket parts). A loose connection means that the contact area is relatively small. In turn, this means high current density at the point of contact. The smaller the contact area, the greater the resistance of the contact. The smaller the contact area, the greater the current density at the point of contact. These two factors contribute to heating of the two parts, the plug blade and the socket. Heating tends to reduce the "springiness" of the socket part, and of the connection between the supply wire and the socket (because they are thermally connected). The heating also tends to degrade the surface of the insulating material in which the conductors are mounted. Heating also enhances oxidation of the plating on the parts, which further increases the resistance of the connections. If the plug-connected appliance is "ON," arcing can occur as the parts expand due to heating and make various intermittant connections. Arc temperatures are very high, and can "burn" the surface of nearby insulating materials via radiation. As the surface degrades, leakages occur across the surfaces. At this point, whether or not the appliance is on or even connected is not a factor. There is a current path between the two poles along the surface of the insulator. This can either be between the socket parts, or between the wired parts. The leakage current causes further heating and micro-arcs where the leakage path opens due to current density. The micro-arcs further damage the insulator until there is nearly continuous micro-arcing. I suggest this is the source of the noise. The heat from the micro- arcing and the resistance of the carbonized surface of the insulator eventually lead to ignition and flames. I admit that this is a hypothesis. I believe that the process is more-or-less correct, but the details may not be correct. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Hi Jim: > I'm curious: given that North American plug blades are >1/2" apart, there > must have been substantial contamination to aid in 120Vac jumping that far > (arcing). Did you identify any sort of contamination or moisture? I don't believe contamination is a significant factor in events such as this one. I believe such events start with a loose connection between the plug and the socket (or between the wire and the socket parts). A loose connection means that the contact area is relatively small. In turn, this means high current density at the point of contact. The smaller the contact area, the greater the resistance of the contact. The smaller the contact area, the greater the current density at the point of contact. These two factors contribute to heating of the two parts, the plug blade and the socket. Heating tends to reduce the "springiness" of the socket part, and of the connection between the supply wire and the socket (because they are thermally connected). The heating also tends to degrade the surface of the insulating material in which the conductors are mounted. Heating also enhances oxidation of the plating on the parts, which further increases the resistance of the connections. If the plug-connected appliance is "ON," arcing can occur as the parts expand due to heating and make various intermittant connections. Arc temperatures are very high, and can "burn" the surface of nearby insulating materials via radiation. As the surface degrades, leakages occur across the surfaces. At this point, whether or not the appliance is on or even connected is not a factor. There is a current path between the two poles along the surface of the insulator. This can either be between the socket parts, or between the wired parts. The leakage current causes further heating and micro-arcs where the leakage path opens due to current density. The micro-arcs further damage the insulator until there is nearly continuous micro-arcing. I suggest this is the source of the noise. The heat from the micro- arcing and the resistance of the carbonized surface of the insulator eventually lead to ignition and flames. I admit that this is a hypothesis. I believe that the process is more-or-less correct, but the details may not be correct. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
No soldered connections. The arc was external to the plug between the blades. Carbonizing and then cutting more carbon in the burn track. Remember the arc was *between* the blades, there was no power going through the cord itself. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Ron Pickard To: m...@california.com Cc: emc-p...@ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 11:01 AM Subject: Re: skinny power cords. > >Hi Robert, > >In your examination, did you find evidence of compression connections with soldered(tinned) leads? >Or, did the compression connections appeared to be loose?. As you might already know, the solder in >such a connection cold flows under the pressure of the connection and after a while this connection >loosens. In my experience, this "loose connection" is the source where the arcing occurs. > >Comments anyone? > >Best regards, > >Ron Pickard >rpick...@hypercom.com > > > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
I'm curious: given that North American plug blades are >1/2" apart, there must have been substantial contamination to aid in 120Vac jumping that far (arcing). Did you identify any sort of contamination or moisture? Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power phone: (604) 422-2546 fax: (604) 420-1591 e-mail: jim.eich...@xantrex.com web: www.xantrex.com -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: Thursday, October 25, 2001 8:50 AM To: Roman, Dan; emc-p...@majordomo.ieee.org Subject: Re: skinny power cords. Just have to jump in here with personal experience: In our bedroom we have a deLonghi radiator heater which uses an extension cord (high cost UL approved) heavy guage #12 wire to power it - when it's used. This extension cord plugs into a "multi outlet" adapter, also heavy duty UL approved. At the time of the incident there was no power being used from this outlet. I was in another room, my wife was sitting on the edge of the bed watching a news blurb on TV when she heard a funny sound, a scritch, scritch. She called to me to come listen. Scritch, scritch, scritch got louder. As I arrived, flames started lapping up the wall from the outlet while still making arcing sounds. The flames were less than 6 inches from curtains. I reached into all this and unplugged the extension cord which luckily stopped the fireworks display. Imagine, if we had not been there. Upon examination, it appeared that an arc had formed between the blades of the extension cord (remember no power at the time). That arc was not sufficient to drop the 15A breaker to the outlet, yet was sufficient to carbonize the UL approved material which further sustained the arc. I posted this to the newsgroup alt.home.repair where a fireman jumped in describing how this exact mechanism is what starts most home fires! Isn't that an encouraging thought! Anyway, a little damn fuse in the plug would not have helped in this circumstance, complete waste of time, much like the main breaker was. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Roman, Dan To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 7:41 AM Subject: RE: skinny power cords. > >I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >in excess of 20A for a short period of time without starting to smoke (heck, >it'll handle close to in excess of 60A for a very very short time without >bursting into flames--not that it was a good experience finding this out). >Point is, the cordage will handle a fault either indefinitely or long enough >for the branch circuit breaker to trip provided you are connected to a 15A >or 20A branch circuit. > >Another data point, you routinely pass more current through the cord when >doing the earthing test and that uses more current than the cord is rated. >Leave the tester on for awhile and the cord does not really heat up either. > >What this list needs is a power cord manufacturer or agency safety engineer >that does power cords to settle this once and for all! > >Dan > >-Original Message- >From: Scott Lacey [mailto:sco...@world.std.com] >Sent: Wednesday, October 24, 2001 7:43 PM >To: Gary McInturff >Cc: emc-p...@majordomo.ieee.org >Subject: RE: skinny power cords. > > > >Gary, >I believe the answer is that the power cord rating of 6 or 10 amps is the >operating current, at which it will have minimum temperature rise. Under >fault conditions it will experience a rather dramatic temperature rise that >is still well below the melting temperature of the insulation. The breaker >or fuse should clear well before the cord is "cooked" to the point of >failure. > >Scott Lacey > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. -
Re: skinny power cords.
Hi Robert, In your examination, did you find evidence of compression connections with soldered(tinned) leads? Or, did the compression connections appeared to be loose?. As you might already know, the solder in such a connection cold flows under the pressure of the connection and after a while this connection loosens. In my experience, this "loose connection" is the source where the arcing occurs. Comments anyone? Best regards, Ron Pickard rpick...@hypercom.com m...@california.com Sent by: To: dan.ro...@intel.com, emc-p...@majordomo.ieee.org owner-emc-pstc@majordomcc: o.ieee.org Subject: Re: skinny power cords. 10/25/01 08:49 AM Please respond to macy Just have to jump in here with personal experience: In our bedroom we have a deLonghi radiator heater which uses an extension cord (high cost UL approved) heavy guage #12 wire to power it - when it's used. This extension cord plugs into a "multi outlet" adapter, also heavy duty UL approved. At the time of the incident there was no power being used from this outlet. I was in another room, my wife was sitting on the edge of the bed watching a news blurb on TV when she heard a funny sound, a scritch, scritch. She called to me to come listen. Scritch, scritch, scritch got louder. As I arrived, flames started lapping up the wall from the outlet while still making arcing sounds. The flames were less than 6 inches from curtains. I reached into all this and unplugged the extension cord which luckily stopped the fireworks display. Imagine, if we had not been there. Upon examination, it appeared that an arc had formed between the blades of the extension cord (remember no power at the time). That arc was not sufficient to drop the 15A breaker to the outlet, yet was sufficient to carbonize the UL approved material which further sustained the arc. I posted this to the newsgroup alt.home.repair where a fireman jumped in describing how this exact mechanism is what starts most home fires! Isn't that an encouraging thought! Anyway, a little damn fuse in the plug would not have helped in this circumstance, complete waste of time, much like the main breaker was. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Roman, Dan To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 7:41 AM Subject: RE: skinny power cords. > >I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >in excess of 20A for a short period of time without starting to smoke (heck, >it'll handle close to in excess of 60A for a very very short time without >bursting into flames--not that it was a good experience finding this out). >Point is, the cordage will handle a fault either indefinitely or long enough >for the branch circuit breaker to trip provided you are connected to a 15A >or 20A branch circuit. > >Another data point, you routinely pass more current through the cord when >doing the earthing test and that uses more current than the cord is rated. >Leave the tester on for awhile and the cord does not really heat up either. > >What this list needs is a power cord manufacturer or agency safety engineer >that does power cords to settle this once and for all! > >Dan > >-Original Message- >From: Scott Lacey [mailto:sco...@world.std.com] >Sent: Wednesday, October 24, 2001 7:43 PM >To: Gary McInturff >Cc: emc-p...@majordomo.ieee.org >Subject: RE: skinny power cords. > > > >Gary, >I
Re: skinny power cords.
Just have to jump in here with personal experience: In our bedroom we have a deLonghi radiator heater which uses an extension cord (high cost UL approved) heavy guage #12 wire to power it - when it's used. This extension cord plugs into a "multi outlet" adapter, also heavy duty UL approved. At the time of the incident there was no power being used from this outlet. I was in another room, my wife was sitting on the edge of the bed watching a news blurb on TV when she heard a funny sound, a scritch, scritch. She called to me to come listen. Scritch, scritch, scritch got louder. As I arrived, flames started lapping up the wall from the outlet while still making arcing sounds. The flames were less than 6 inches from curtains. I reached into all this and unplugged the extension cord which luckily stopped the fireworks display. Imagine, if we had not been there. Upon examination, it appeared that an arc had formed between the blades of the extension cord (remember no power at the time). That arc was not sufficient to drop the 15A breaker to the outlet, yet was sufficient to carbonize the UL approved material which further sustained the arc. I posted this to the newsgroup alt.home.repair where a fireman jumped in describing how this exact mechanism is what starts most home fires! Isn't that an encouraging thought! Anyway, a little damn fuse in the plug would not have helped in this circumstance, complete waste of time, much like the main breaker was. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Roman, Dan To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, October 25, 2001 7:41 AM Subject: RE: skinny power cords. > >I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well >in excess of 20A for a short period of time without starting to smoke (heck, >it'll handle close to in excess of 60A for a very very short time without >bursting into flames--not that it was a good experience finding this out). >Point is, the cordage will handle a fault either indefinitely or long enough >for the branch circuit breaker to trip provided you are connected to a 15A >or 20A branch circuit. > >Another data point, you routinely pass more current through the cord when >doing the earthing test and that uses more current than the cord is rated. >Leave the tester on for awhile and the cord does not really heat up either. > >What this list needs is a power cord manufacturer or agency safety engineer >that does power cords to settle this once and for all! > >Dan > >-Original Message- >From: Scott Lacey [mailto:sco...@world.std.com] >Sent: Wednesday, October 24, 2001 7:43 PM >To: Gary McInturff >Cc: emc-p...@majordomo.ieee.org >Subject: RE: skinny power cords. > > > >Gary, >I believe the answer is that the power cord rating of 6 or 10 amps is the >operating current, at which it will have minimum temperature rise. Under >fault conditions it will experience a rather dramatic temperature rise that >is still well below the melting temperature of the insulation. The breaker >or fuse should clear well before the cord is "cooked" to the point of >failure. > >Scott Lacey > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
I agreed completely with Scott. A 6 to 9 foot 18AWG cord will handle well in excess of 20A for a short period of time without starting to smoke (heck, it'll handle close to in excess of 60A for a very very short time without bursting into flames--not that it was a good experience finding this out). Point is, the cordage will handle a fault either indefinitely or long enough for the branch circuit breaker to trip provided you are connected to a 15A or 20A branch circuit. Another data point, you routinely pass more current through the cord when doing the earthing test and that uses more current than the cord is rated. Leave the tester on for awhile and the cord does not really heat up either. What this list needs is a power cord manufacturer or agency safety engineer that does power cords to settle this once and for all! Dan -Original Message- From: Scott Lacey [mailto:sco...@world.std.com] Sent: Wednesday, October 24, 2001 7:43 PM To: Gary McInturff Cc: emc-p...@majordomo.ieee.org Subject: RE: skinny power cords. Gary, I believe the answer is that the power cord rating of 6 or 10 amps is the operating current, at which it will have minimum temperature rise. Under fault conditions it will experience a rather dramatic temperature rise that is still well below the melting temperature of the insulation. The breaker or fuse should clear well before the cord is "cooked" to the point of failure. Scott Lacey --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
Gary, I believe the answer is that the power cord rating of 6 or 10 amps is the operating current, at which it will have minimum temperature rise. Under fault conditions it will experience a rather dramatic temperature rise that is still well below the melting temperature of the insulation. The breaker or fuse should clear well before the cord is "cooked" to the point of failure. Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gary McInturff Sent: Wednesday, October 24, 2001 12:06 PM To: EMC-PSTC (E-mail) Subject: skinny power cords. Fuses and breakers etc, are provided to protect the wiring downstream from these devices. A 15 amp breaker is allowed to have 14 AWG wire attached and run all though my house, and terminates in a 15 amp rated receptacle - parallel blade with ground pin. Why then can I plug in a computer that has only a 6 or 10 amp rated power cord? Surely, its not because the computer has supplemental fusing at 2 amps or whatever. That 2 amp fuse can't protect the wiring between it and the 15 amp breaker in my garage from prolonged operation at 15 amps. The breaker is completely happy running at that value so the wire just sits there and cooks! One would think that any cord rated less than 15 amps, would have to be terminated in a plug that doesn't mate with the wall outlet, much like a 15 amp connector plugged into a 20 amp outlet. Gary --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
RE: skinny power cords.
I'll join the speculation... I think it is also based on the likelihood of undetected damage to the cord leading to a situation. The cord lengths are limited by standards, they are jacketed with materials designed to withstand some abuse, the condition is easily (albeit rarely) inspected by the user, they are not supposed to be physically attached to the wall (so no fear of damage by a metal cable clamp for example), and so on. The wiring in your walls, by comparison, may be more at risk, since it can't be inspected, it is stapled to the studs, and you're always drilling or pounding nails into walls having no idea whether or not there is wiring behind the drywall. Regards, Jim Eichner, P.Eng. Manager, Engineering Services Xantrex Technology Inc. Mobile Power web: www.xantrex.com <http://www.xantrex.com> Any opinions expressed are those of my invisible friend, who really exists, and frequently has gas. Honest. -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Wednesday, October 24, 2001 12:21 PM To: gary.mcintu...@worldwidepackets.com Cc: emc-p...@ieee.org Subject: Re: skinny power cords. Hi Gary: Somewhere in my past, I've heard the rationale for this conundrum. I'm just guessing here. Power cords and similar mains devices are sized based on rated load, and are not sized based on fault-condition load. The requirement should be that, under fault conditions, the device is capable of withstanding the fault until the overcurrent device operates without igniting or otherwise causing a hazard. It can get hot; indeed, it can exceed rated temperature under the fault, and it can fail, but it should not ignite or otherwise cause a hazardous condition. A power cord is supposed to be sufficiently robust as to withstand the rigors of use. There are different degrees of robustness according to use. In other words, the power cord itself is not expected to fail under normal conditions of use. So, the power cord should only be subject to load faults. Since the load is protected against faults, the fault-protection in the load also provides fault-protection for the power cord. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Coggs. (Compliance old guys and gals) Appliance incoming fuses fitted or not. The other problem scenario with 'skinny power cords' on hand-held products is where the cord enters the appliance and, despite all the patent anti-flex cord grommets, the insulation breaks down with stress and the skinny power cord becomes a five foot length of fuse wire. The problem is reduced in the UK where the most popular plug style in domestic and commercial applications is fitted with a HBC cartridge fuse. PROVIDING the end user does not change the fuse for a higher rating. Three pin 13 A fused plug to BS1363. ( Oh how UL laughed at the size of our 'chunky' plugs but did admit they were a good idea) British Std Certified fuse cartridges to BS1362 are available in 2, 3, 5, 7, 10 and 13 A ratings. Eric. PS. George - you didn't get the date wrong in your last mail did you ? On 24 Oct 01 at 14:40, geor...@lexmark.com wrote: > > > > Gary, > > It was always my understanding that house fuses/breakers were to protect > all the upstream stuff, e.g. service entry box, external transformers etc. > They cannot realistically protect downstream stuff, as they have no > knowledge of how much current is too much for a given appliance. However, > the house wiring should be able to carry a current up to that of the fuse > or CB rating. > > ITE manufacturers must protect their own product by the use of incoming > fuses, CBs, etc. A fixed line cord is part of the product. Hence, the > product fuse must blow before a "skinny" line cord on the product would > melt down. For example, suppose a device is rated to draw 2.5A (electric > razor?) and uses a "skinny" line cord at that rating. If an internal > fault draws 14A, it might melt down the cord or the device, but it should > not harm house wiring rated up to 15A. > > Of course, I have been wrong before. I think it was 1961. > > George > > > -- Forwarded by George Alspaugh/Lex/Lexmark on 10/24/2001 > 02:31 PM --- > > Gary McInturff on > 10/24/2001 12:06:00 PM > > Please respond to Gary McInturff > > > To: "EMC-PSTC (E-mail)" > cc:(bcc: George Alspaugh/Lex/Lexmark) > Subject: skinny power cords. > > > > > Fuses and breakers etc, are provided to protect the wiring > downstream from these devices. A 15 amp breaker is allowed to have 14 AWG > wire attached and run all though my house, and terminates in a 15 amp rated > receptacle - parallel blade with ground pin. > Why then can I plug in a computer that has only a 6 or 10 amp rated > power cord? Surely, its not because the computer has supplemental fusing at > 2 amps or whatever. That 2 amp fuse can't protect the wiring between it and > the 15 amp breaker in my garage from prolonged operation at 15 amps. The > breaker is completely happy running at that value so the wire just sits > there and cooks! > One would think that any cord rated less than 15 amps, would have > to be terminated in a plug that doesn't mate with the wall outlet, much like > a 15 amp connector plugged into a 20 amp outlet. > Gary > > > > > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > * Your best support in "TESTING" situations * * INTERTest Systems UK * * International Product Certification * *ONE-STOP-SHOP for ALL testing * *PO Box 321 - Bucks HP9 1XJ - England * * ++44 (0)1494 673438 Fax 678868* * INTERTest Systems UK is the trading name of * * the test laboratory of E M Consulting Ltd. * --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Ri
Re: skinny power cords.
Hello Gary, Sounds like your making a case for the wider adoption of the UK system with fused plugs rated to protect the power cord Nick Rouse - Original Message - From: "Gary McInturff" To: "EMC-PSTC (E-mail)" Sent: Wednesday, October 24, 2001 5:06 PM Subject: skinny power cords. > > > Fuses and breakers etc, are provided to protect the wiring > downstream from these devices. A 15 amp breaker is allowed to have 14 AWG > wire attached and run all though my house, and terminates in a 15 amp rated > receptacle - parallel blade with ground pin. > Why then can I plug in a computer that has only a 6 or 10 amp rated > power cord? Surely, its not because the computer has supplemental fusing at > 2 amps or whatever. That 2 amp fuse can't protect the wiring between it and > the 15 amp breaker in my garage from prolonged operation at 15 amps. The > breaker is completely happy running at that value so the wire just sits > there and cooks! > One would think that any cord rated less than 15 amps, would have > to be terminated in a plug that doesn't mate with the wall outlet, much like > a 15 amp connector plugged into a 20 amp outlet. > Gary > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
Hi Gary: Somewhere in my past, I've heard the rationale for this conundrum. I'm just guessing here. Power cords and similar mains devices are sized based on rated load, and are not sized based on fault-condition load. The requirement should be that, under fault conditions, the device is capable of withstanding the fault until the overcurrent device operates without igniting or otherwise causing a hazard. It can get hot; indeed, it can exceed rated temperature under the fault, and it can fail, but it should not ignite or otherwise cause a hazardous condition. A power cord is supposed to be sufficiently robust as to withstand the rigors of use. There are different degrees of robustness according to use. In other words, the power cord itself is not expected to fail under normal conditions of use. So, the power cord should only be subject to load faults. Since the load is protected against faults, the fault-protection in the load also provides fault-protection for the power cord. Best regards, Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Re: skinny power cords.
I am NOT an expert in this field so I could likely stand some educating but the following seem to me to be common sense: 1) Household circuit breakers protect household wiring - only. They prevent wiring damage and fires. There is no practical way to provide breakers for every different kind of load. 2) I extrapolate your logic to imply that every appliance, including low power consumers such as a clock radios, would be forced to use AWG 12 power cords. 3) If an appliance such as a computer does have an internal fuse between power cord and power supply such that any short in the appliance will draw current through the fuse, why would the power cord have to be rated at any higher ampacity than the fuse itself, other than a reasonable safety margin? In other words, what is wrong with using a 6 or 10 Amp rated power cord with a device fused at 2 Amps, to use your example? -- >From: Gary McInturff >To: "EMC-PSTC (E-mail)" >Subject: skinny power cords. >Date: Wed, Oct 24, 2001, 11:06 AM > > > Fuses and breakers etc, are provided to protect the wiring > downstream from these devices. A 15 amp breaker is allowed to have 14 AWG > wire attached and run all though my house, and terminates in a 15 amp rated > receptacle - parallel blade with ground pin. > Why then can I plug in a computer that has only a 6 or 10 amp rated > power cord? Surely, its not because the computer has supplemental fusing at > 2 amps or whatever. That 2 amp fuse can't protect the wiring between it and > the 15 amp breaker in my garage from prolonged operation at 15 amps. The > breaker is completely happy running at that value so the wire just sits > there and cooks! > One would think that any cord rated less than 15 amps, would have > to be terminated in a plug that doesn't mate with the wall outlet, much like > a 15 amp connector plugged into a 20 amp outlet. > Gary > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
