SES Panel ratings

[stanraeolsen]

We have installed an approved (by the Utility) a 400 Amp Square D Combination Service entrance whic has a rating of 22KIC. During a recent inspection the City Inspector stated that it needs to be rated at 36 KIC min. Tghis has been our normal single family dwelling configuration. Where in the NEC does it specify the rating of a SES. Or where can I find information to argue with the Inspector (usually not a good thing)

 

[suemarkp]

The combination service entrance must be rated for the available fault current. The available current depends on the size transfromer feeding you, the size wires feeding you, and the length of those wires. You could also have some local rules that establish minimums you must meet whether they make sense or not.

If you post the transformer KVA, service drop/lateral size and length, someone here may be able to give you an approximate value to design for. You could also ask the power company what they think the available fault current is, and the inspector may be more inclined to believe them especially if its in writing.

I was worried about this for mine, as the 320/400A meter enclosure is only rated 10KAIC and my main panels are 22KAIC. The 22K is plenty, but even with my puny service drop and 50 KVA transformer, I believe the available fault current is less than 10 KVA.

 

[mdshunk]

During a recent inspection the City Inspector stated that it needs to be rated at 36 KIC min.

Does the city inspector do his own engineering calcs? I'd really like to know his justification on that one. Maybe he's right, maybe he's not; but I might guess he picked that out of the clear blue sky. I think I'd start by asking him on what grounds he feels you need 36K.

 

[mpd]

the utility should be able to give you the available fault current, and pass it on to the inspector, I have asked for it several times from contractors before I send a cut card