Hi Lauren,
MCCB (molded case circuit breakers) get hot when they are run close to their handle rating, even open bench. If installed in a panel (dead air space) at 40C ambient temperature, I would expect they would easily exceed 50C on their molded case long before say 3 hours have expired (continuous current as defined in NFPA 70). Their terminals are rated for 60C wire, so those terminals (the internal parts connected to them) can get at least that hot. If simply heat-soaked at zero current at 50C, I'd say you have no worries. It is always wise to write to the manufacturer of the circuit breaker and ask them if they can check the "conditions of acceptability" which normally accompanies any UL recognition. Include ALL your test conditions in your correspondence. From: Lauren Crane <[email protected]> Sent: Friday, January 5, 2024 4:48 PM To: [email protected] Subject: [PSES] Is certification 'voided' by improper operational conditions? Hello Experts, If I have UL certified component and operate it for a period of time outside its specified conditions of operation, and then return the conditions to specified levels, is it appropriate to still think of the component as certified, or is the certification somehow voided by this accident? For example, a circuit breaker rated for 40degC max ambient run at 50degC ambient for 8 hours and then ambient temp brought down to 30degC. Best Regards, -Lauren Happy to receive recall-opinions and educated guesses but would love 'chapter and verse' citations if available. LAM RESEARCH CONFIDENTIALITY NOTICE: This e-mail transmission, and any documents, files, or previous e-mail messages attached to it, (collectively, "E-mail Transmission") may be subject to one or more of the following based on the associated sensitivity level: E-mail Transmission (i) contains confidential information, (ii) is prohibited from distribution outside of Lam, and/or (iii) is intended solely for and restricted to the specified recipient(s). If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are hereby notified that any disclosure, copying, distribution or use of any of the information contained in or attached to this message is STRICTLY PROHIBITED. If you have received this transmission in error, please immediately notify the sender and destroy the original transmission and its attachments without reading them or saving them to disk. Thank you. Confidential - Limited Access and Use _____ 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 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
