Regarding "I recall reading in one or two UL standards that if both hazardous and SELV wires are insulated to the higher working voltage of the two, no separation or barrier is required." I've also seen this requirement, and I explain it under the rationale that it should take two separate insulation failures for the hazardous voltage to be able to pass into the SELV circuit. One would be the failure of the insulation on the hazardous voltage wiring, and the other failure would be of the insulation on the SELV wiring. Mike Sherman Sherman PSC LLC
> On 10/18/2024 2:49 PM CDT Ralph McDiarmid <[email protected]> wrote: > > > > Hi John, > > > > I never understood rationale for segregating and separating insulated wires > of different circuit from one another. I can understand the need to separate > and secure insulated wires from uninsulated live parts and SELV wires from > hazardous live bare parts. I recall reading in one or two UL standards that > if both hazardous and SELV wires are insulated to the higher working voltage > of the two, no separation or barrier is required. > > > > Ralph > > > > From: John Woodgate <[email protected]> > Sent: October 18, 2024 11:02 AM > To: [email protected] > Subject: Re: [PSES] Separation of AC and DC Conductors in Control Cabinet > > > > A quarter-inch doesn't seem big enough to have any effect beyond air > insulation. On the other hand, why is it necessary to separate insulated AC > and DC cables, as long as they are identified by colour or shape. Securing is > important: cables can jump about under high-current fault conditions, and can > become detached from terminals. > > On 2024-10-18 18:30, Ralph McDiarmid wrote: > > > > > Hi James, > > > > > > > > Most UL standards I’ve work with require segregation of factory-installed > > wiring by clamping or routing to provide a secure and permanent separation. > > For field wiring compartments, a barrier between conductors of different > > circuits is needed and openings in the wiring compartment to facility that > > separation. For a control cabinet intended for installation in the USA, I > > would consult UL 508 Industrial Control Equipment, and that standard calls > > for a minimum separation distance of ¼ inch. > > > > > > > > Ralph > > > > > > > > From: James Hulbert <[email protected]> > > mailto:[email protected] > > Sent: October 18, 2024 9:44 AM > > To: [email protected] mailto:[email protected] > > Subject: [PSES] Separation of AC and DC Conductors in Control Cabinet > > > > > > > > Happy Friday! Within a control cabinet, AC and DC conductors should not be > > co-mingled. Is there a specification for minimum separation distance? A > > minimum separation of 2 inches seems to be a standard practice, but is > > there a specification or standard that calls that out? Thank you. > > > > > > > > Jim Hulbert > > > > This email message may contain confidential, proprietary and/or privileged > > information. It is intended only for the use of the intended recipient(s). > > If you have received it in error, please immediately advise the sender by > > reply email and then delete this message. No one other than the intended > > recipient may disclose, copy, distribute or use the information contained > > in this message. > > > > > > --------------------------------------------- > > > > 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] mailto:[email protected] > > > > All emc-pstc postings are archived and searchable on the web at: > > https://www.mail-archive.com/[email protected]/ > > https://www.mail-archive.com/[email protected]/%20 > > > > Website: https://ewh.ieee.org/soc/pses/ https://ewh.ieee.org/soc/pses/ > > Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to > > unsubscribe) https://ewh.ieee.org/soc/pses/list.html > > List rules: https://ewh.ieee.org/soc/pses/listrules.html > > > > For help, send mail to the list administrators: > > Mike Sherman at: [email protected] mailto:[email protected] > > Rick Linford at: [email protected] mailto:[email protected] > > > > For policy questions, send mail to: > > Jim Bacher at: [email protected] mailto:[email protected] > > > > > > --------------------------------------------- > > > > To unsubscribe from the EMC-PSTC list, click the following link: > > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > > > > > --------------------------------------------- > > > > 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] mailto:[email protected] > > > > All emc-pstc postings are archived and searchable on the web at: > > https://www.mail-archive.com/[email protected]/ > > https://www.mail-archive.com/[email protected]/%20 > > > > Website: https://ewh.ieee.org/soc/pses/ https://ewh.ieee.org/soc/pses/ > > Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to > > unsubscribe) https://ewh.ieee.org/soc/pses/list.html > > List rules: https://ewh.ieee.org/soc/pses/listrules.html > > > > For help, send mail to the list administrators: > > Mike Sherman at: [email protected] mailto:[email protected] > > Rick Linford at: [email protected] mailto:[email protected] > > > > For policy questions, send mail to: > > Jim Bacher at: [email protected] mailto:[email protected] > > > > > > --------------------------------------------- > > > > To unsubscribe from the EMC-PSTC list, click the following link: > > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > > > > -- > > OOO - Own Opinions Only > > Best Wishes > > John Woodgate > > Keep trying > > > http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient > > Virus-free.www.avg.com > http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient > > > > > --------------------------------------------- > > 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: > https://www.mail-archive.com/[email protected]/ > > > > Website: https://ewh.ieee.org/soc/pses/ https://ewh.ieee.org/soc/pses/ > Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to > unsubscribe) https://ewh.ieee.org/soc/pses/list.html > List rules: https://ewh.ieee.org/soc/pses/listrules.html > > For help, send mail to the list administrators: > Mike Sherman at: [email protected] mailto:[email protected] > Rick Linford at: [email protected] mailto:[email protected] > > For policy questions, send mail to: > Jim Bacher at: [email protected] mailto:[email protected] > > > --------------------------------------------- > > To unsubscribe from the EMC-PSTC list, click the following link: > https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1 > - ---------------------------------------------------------------- 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: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
