Actually, the rule (Article 210-22 of the NEC) has nothing to do with protecting the plugs or the wiring. The 80% rule is there to make sure the branch circuit overcurrent protective device (fuse or CB) doesn't overheat.
----- Original Message ----- From: "Robert Johnson" <john...@itesafety.com> To: <emc-p...@majordomo.ieee.org> Sent: Thursday, August 29, 2002 10:50 PM Subject: RE: requirements for ITE power cords > Sorry to knock your "substantially built" comment, but the derating is > not based on the plug. In fact the 15 and 20 amp plugs are the same > construction with different configuration. Both can be used at full > rating. The circuit they are used in contains the limitation. > The derating on North American circuits is based on thermal > considerations. The derating (80% of rated load) applies to all > "continuous loads" which are defined as over 3 hours. ITE is considered > continuous by default. The long term degradation of wire insulation is > related to temperature and time. Given considerations such as > neighboring conductors, thermal insulation, current, duration, wire > gauge, etc, this is one way the code allows for higher short term loads. > > Bob Johnson > ITE Safety > > > -----Original Message----- > From: owner-emc-p...@majordomo.ieee.org > [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of John Allen > Sent: Thursday, August 29, 2002 5:28 PM > To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org > Subject: Re: requirements for ITE power cords > > > Hi Folks > > Sorry to be late in replying on this one - and not really trying to > disagree - but I think you will find that the 125% rule is a "North > American" convention and also followed by countries which use similar > installation practice (i.e. that have plugs with quite small > blades/pins!). > > The same rule does not - to the best of my knowledge - apply in Europe > (& > certainly not in the UK) and other countries that follow European > installation practice where derating is not required as our plugs are > more > substantially built! > > Therefore we can use a 13 (UK) or 16A (Europe) cable and 13A or 16A plug > on > an equipment rated at 13A/16A respectively, e.g: re it applies in > respect of > the EN60950 standard. > > Regards > > John Allen > ----- Original Message ----- > From: <richwo...@tycoint.com> > To: <emc-p...@majordomo.ieee.org> > Sent: Thursday, August 15, 2002 11:59 AM > Subject: RE: requirements for ITE power cords > > > > > > George, the ITE safety standards require that the plug be rated for at > least > > 125% of the equipment rating. I believe that the US National > Electrical > Code > > has the same requirement. > > > > Richard Woods > > Sensormatic Electronics > > Tyco International > > > > > > -----Original Message----- > > From: George Stults [mailto:george.stu...@watchguard.com] > > Sent: Wednesday, August 14, 2002 6:28 PM > > To: 'emc-p...@majordomo.ieee.org' > > Subject: requirements for ITE power cords > > > > > > > > Hello Group, > > > > Recently my purchasing department asked me to recommend standards for > power > > cords. These are detachable power cords for ITE equipment, both > 3-wire > and > > 2-wire. > > Typically the cords are marked with one or more of CSA, UL, (Dentori > T). > > The ones we get are typically rated from 6 to 10 times the required > current > > for a given product. > > > > My question is, are there required or recommended power cord design > margins > > for current, voltage, power, temperature range, insulation, etc. > spelled > out > > in IEC/EN 60950 or UL1950 or MIL-HDBK 217 or elsewhere? > > > > Thanks in advance > > > > George Stults > > > > > > ------------------------------------------- > > 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: > > Ron Pickard: emc-p...@hypercom.com > > Dave Heald: davehe...@attbi.com > > > > 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: > > http://ieeepstc.mindcruiser.com/ > > Click on "browse" and then "emc-pstc mailing list" > > > > ------------------------------------------- > > 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: > > Ron Pickard: emc-p...@hypercom.com > > Dave Heald: davehe...@attbi.com > > > > 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: > > http://ieeepstc.mindcruiser.com/ > > Click on "browse" and then "emc-pstc mailing list" > > > > ------------------------------------------- > 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: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > 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: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > ------------------------------------------- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com 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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
