Dave, I think it depends on whether you have an internal neutral derived from the secondary of a control transformer. If you do, and that neutral is bonded to the grounding/earthing connection at the mont of supply, then the DC common could also be identified as a neutral wire IF the DC common is earthed/grounded to the same point.
Brown is used for the 1P live conductor in Europe, so I wouldn’t suggest that for DC. The reason for the Brown/Blue colour coding in three-wire sensor cables is that the manufacturer is assuming that all devices connected with those M8, M12, M18 connectors COULD be AC devices. Because DC sensors live below the 50 Vac / 75 Vdc threshold in the LVD, the assumption is that the colours don’t matter for DC. Ultimately, if you put a wire colour table at the start of your electrical drawing set, and follow that throughout, you’re in compliance. You could use all black wire and just number the conductors, and still be compliant with NFPA 79 and EN/IEC 60204-1, but your electricians would hate you. :-) Doug Nix [email protected] +1 (519) 729-5704 > On 8-Oct-15, at 16:57, Nyffenegger, Dave <[email protected]> wrote: > > Hi Folks, > > There's been plenty of discussion here in the past on AC wire colors and > neutral. With regards to DC, NFPA 79 and UL 508 A also define BLUE for > ungrounded dc control circuits and WHITE with BLUE stripe for grounded dc > current-carrying control circuit conductor. EN 60204-1 defines BLACK for > a.c. and d.c. power circuits and BLUE for d.c. control circuits. Machinery > of course is typically comprised of AC power distribution and loads and DC > controls including many sensors and actuators. Many manufacturers of 3 wire > DC sensors seem to have standardized on using BROWN for DC power (I.e. > 24VDC), BLUE for grounded dc current-carrying control circuit conductor (DC > common), and BLACK for the signal. This seems inconsistent with the above > standards. Does anyone know if there is another standard behind what the > sensors are using or any reason for the discrepancy? Comments? > > > David P. Nyffenegger, PMP, SM-IEEE > Product Development Manager > > - > ---------------------------------------------------------------- > 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://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 <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher: <[email protected]> > David Heald: <[email protected]> - ---------------------------------------------------------------- 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://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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
