Keep this in mind. The US NEC allows power cords to be made from 18AWG wire even though they can be plugged into a 20 amp circuit.
Protective bonding Test at 40 amps for 4 minutes will melt the insulation of 18AWG wire. Even internal 18AWG hookup wire used as the Protective bonding conductor (Green/Yellow insulation) will melt during the 40 amp bond test at 4 minutes. So we switched to 16AWG power cords (minimum size) and all internal Protective bonding conductors are at a minimum 14AWG. Just to be on the safe side. Canada has some rule about the Protective bonding conductor cannot be smaller than the current carrying conductors in the power cord. And since standard PC type power cords (NEMA plug to IEC connector) can come in 18AWG, 16AWG, or 14AWG, we use 14AWG internal protective bonding conductors to meet Canada's requirements no matter what size power cord is used with our equipment. The Other Brian -----Original Message----- From: Rodney Davis [mailto:rodney.da...@mitel.com] Sent: Thursday, March 03, 2016 3:36 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Insulation testing Yes in Canada and USA the line current is deemed to be 20 amps therefore 2 times = 40 Amps. in the old days the branch was considered 15A. This changed (really guessing here so please no arguments) 8 years ago. Rodney Davis - Canada ________________________________________ From: Brian O'Connell <oconne...@tamuracorp.com> Sent: Thursday, March 3, 2016 3:00 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Insulation testing Correct -> CSA No. 0.4 specifies 40A test level. Brian From: Mike Sherman ----- Original Message ----- [mailto:msherma...@comcast.net] Sent: Thursday, March 03, 2016 11:52 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Insulation testing I've always thought the Canada requirement was 40 amps for 2 minutes. Mike Sherman Graco Inc. Sent from Xfinity Connect Mobile App ------ Original Message ------ From: Richard Nute To: EMC-PSTC@LISTSERV.IEEE.ORG Sent: March 3, 2016 at 1:37 PM Subject: Re: [PSES] Insulation testing Hi Ralph: It seems that the standards are treating functional ground connections (those that do not pass a bonding impedance test) as a 0th fault, not a single fault. For the bonding impedance test (fault current), what would be the test current? Would it be twice the rating of the mains over-current protection? (e.g. 2 x 15A breaker rating) I don't know what a "0th" fault is. A functional earth must be double- or reinforced-insulated from the mains (or any other voltage exceeding ELV). This is because (if only basic insulation between the mains and the functional earth conductor) a fault of the basic insulation may allow the full current of the mains to flow in the functional earth conductors, which may not be able to carry this current. If the functional earth conductor should open, mains voltage will appear on the remaining functional earth circuits and may cause a severe electric shock. If the fault of basic insulation results in a zero-impedance to earth, the current is set by the source impedance and lasts until the overcurrent device operates. Overcurrent devices take time to operate. For most overcurrent devices, the time to operate depends on the magnitude of the fault current. Most overcurrent devices are rated either 1 or 2 minutes at twice rated current. So, the worst case is 2 minutes at 2x rated current. In the USA, on 15-amp and 20-amp circuits, the fault current is taken as 25 amps for 1 minute. In Canada, the fault current is taken as 30 amps for 2 minutes. (Most constructions will pass both tests.) Best regards, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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Thank you. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
