Hi Scott:
You are correct: no product standards specify wire color for internal mains circuits. Never. Way back, some certification engineers required internal mains wiring to be the same color as the power cord, which is the same color as the building wiring: blue-brown or white-black for neutral and phase (line) conductors. This was a "jawbone" requirement, that is, it was a verbal requirement, not a written requirement. (I went through this experience.) This was a natural extension when we used attached power cords, and the colors came into the product via the power cord. Imagine the certification engineer noting the color of the power cord wires; then, at the first wiring strip, a change to internal colors. He didn't think it made sense, so he required the colors be maintained within the product -- for the safety of technicians working on the product so they could identify the mains circuits. This did make a bit of sense before the advent of SMPSs. Back in the days of linear power supplies, the mains simply went through the fuse and power switch and directly to the transformer. Both the fuse and switch had to be in the phase or line conductor (black) so this made the determination quite easy. So, no big deal to use the power cord colors for internal wires. With the advent of SMPSs, polarity is nonsense at the output of the rectifier. Blue-brown is the European wire color for neutral and phase. Since there was no written requirement for wire color, UL readily accepted blue-brown. Don't sweat it, Rich > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Scott Douglas > Sent: Friday, April 06, 2012 5:01 PM > To: [email protected] > Subject: Color of Mains Wiring > > > For ITE (60950-1) and A/V (60065) products a question of > color came up > today. > > I told an ODM they had to use Brown (Line), Blue (Neutral), and > Green/Yellow (PE) colors for AC Mains wiring inside the product. They > replied that the current standard does not require Brown and Blue. I > looked in my several years old copies of the standards (UL, CSA, IEC) > and the only color I can find is Green/Yellow for Protective Earth. > > For years I have been requiring and getting AC Mains within a > product to > be Brown, Blue, Green/Yellow. For whatever reason, this just > that way it > was and everybody knew it and used those colors. > > Since I cannot find that requirement in either of the standards, can > anyone tell my why I have been insisting on them all these > years? Where > does the requirement come from? BFIF, I also recall that UL accepts > Brown, Blue, and Green/Yellow within domestic products. So where does > that that allowance/acceptance come from? > > This is not for external power cords, but hook-up wire inside > the product. > > I am looking for page, paragraph, and rule - something in > writing just > so I know that I have not been on the happy wagon all these years. > > Here's to hoping someone can tell me I have not been dreaming > all this time. > > Regards, > Scott > - ---------------------------------------------------------------- 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 <[email protected]> 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://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
