If I understand your question correctly, then a failure of a control wire would result in the loss of two, independent safety functions, each function being provided by a separate component. That would result in a loss of single-fault tolerance, a central principle of product safety. IEC62368-1 is a good, modern reference. The principles of product safety described in the old IEC60950-1 is another.
To determine if the loss of two independent safety functions in your equipment results in a hazard, then you likely need to do an FMEA (Failure Mode & Effects Analysis). Ralph From: Steve Brody <[email protected]> Sent: Thursday, August 8, 2024 8:58 AM To: [email protected] Subject: [PSES] Fault Exclusion Experts: I have been told that: 'if you have two safety components in the same electrical cabinet you can connect them with a single control wire, you can exclude faults against that wire as a fault that needs to be considered for safety calculations.' It is logical if the two safety components' are redundant. But if they have different functions? I have not been able to confirm that in any standard. If you agree that this statement is correct, then I would appreciate your rationale and if possible a reference to chapter and verse in a standard or risk assessment document. Thanks, Steve Brody [email protected] <mailto:[email protected]> C - 603 617 9116 _____ 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 <https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1> &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
