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AIC ratings #28269
08/15/03 11:35 AM
08/15/03 11:35 AM
R
rmiell  Offline OP
Member
Joined: Nov 2000
Posts: 242
La Junta, Co. USA
If you have a panelboard rated 22k AIC, and you install a breaker rated only 10k AIC, and assuming no series combo ratings, is the complete setup rated 10k or 22k?

Where is this addressed in the NEC?

Thanks

Rick Miell

Work Gear for Electricians and the Trades
Re: AIC ratings #28270
08/15/03 12:31 PM
08/15/03 12:31 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
If the available current at the line side of the breaker exceeds 10k, you can't install that breaker. See 110.9. I guess you would have to say that the set-up is only good for the 10k after you install the 10k breaker. It doesn't really change the rating of the panel or the other breakers, but prohibits the use of the panel with the 10k breaker on a system where the available fault current exceeds 10k.
Don


Don(resqcapt19)
Re: AIC ratings #28271
08/15/03 04:10 PM
08/15/03 04:10 PM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Don,
Would the NEC allow a breaker rated lower than the prospective fault current if there is a properly rated OCPD upstream?

We commonly use domestic breakers rated 6000A AIC here on supplies capable of delivering a much higher current. The higher AIC rating of the main cartridge fuse is considered adequate protection against a dead short.

Re: AIC ratings #28272
08/15/03 11:05 PM
08/15/03 11:05 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Paul,
If it is a listed and tested "series rated" system, a lower rated breaker may be used. This system cannot be calculated based on let through curves or any other type of calculation. It must be tested by a testing lab and listed.
Don


Don(resqcapt19)
Re: AIC ratings #28273
08/16/03 03:44 AM
08/16/03 03:44 AM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Ah, so only if the actual series combination is listed for such use then. Thanks.


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