equipment short circuit rating

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winslowfam

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Location
VA
Hi...NEC 110.9 and 110.10 require that certain parts of an electrical installation be rated for the available fault current (110.9) and have the ability to clear a fault condition without damaging the "electrical components of the circuit" (110.10). Does this mean that every device connected to the power system, such as HVAC control panels, UPS's, Inverters, along with breaker panels (breaker panels always have an AIC rating), etc. that is UL listed must have an AIC rating from the OEM? Or is it limited to only some types of electrical equipment? Thanks.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Hi...NEC 110.9 and 110.10 require that certain parts of an electrical installation be rated for the available fault current (110.9) and have the ability to clear a fault condition without damaging the "electrical components of the circuit" (110.10). Does this mean that every device connected to the power system, such as HVAC control panels, UPS's, Inverters, along with breaker panels (breaker panels always have an AIC rating), etc. that is UL listed must have an AIC rating from the OEM? Or is it limited to only some types of electrical equipment? Thanks.

Every device must be applied within its limits. The NEC does not specifically require third party testing/listing of short circuit ratings.

Protective devices (fuses and breakers) are the only things that have AIC ratings. Everything else, including panel board bussing, has an SCCR. The term SCCR (short circuit current rating) is now used instead of the older term "withstand rating".
 

winslowfam

Senior Member
Location
VA
Thanks...I checked the website link adn it said the site could not be found. Do you have another link I could look at?
 

winslowfam

Senior Member
Location
VA
Would UL require a withstand rating or SCCR for anything with a UL label that is powered from the distribution system? I have a client who has bought an inverter to bring solar power into a switchboard and the OEM is saying he doesn't have any fault current rating for his inverter...just an AIC rating for its main breaker.
 
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