Emergency Generator power

[AES1005]

I have a 400 amp service 3 phase delta (2x200 amp) panels in a community shelter. I have installed a 400 amp rated manual transfer switch. (500 mcm) wire from main power. My question is the county which is supplying the portable emergency generators has several generators that they use in different places, so you may not get the same generator, most of their generators have outputs up to 175kw and above. The generator planned for use has an 800 ampere circuit breaker for the output, Now should i install a fused disconnect on the building side / or 400 amp circuit breaker to protect the cable coming from the generator to the manual transfer switch? So the max amps would be 400 or would the existing circuit breakers on each panel of 200 amps be acceptable the the wire protection. What are some code references?

Appreciate comments.:?:?

 

[augie47]

IMO, the conductors coming from the generator should be protected by an OCP device on the generator.
As far as your installation goes, there is little difference from the utility conductors to your transfer switch and the generator ones.

 

[AES1005]

Yes their generator has an OCP 800 amps which will feed (only in emergency situations) to the transfer switch rated for 400 amps.

 

[AES1005]

Okay, I think I found an answer, 445.13 Ampacity of the conductors from the generator terminals to the first distribution device shall not be less than 115 % of the nameplate current rating of the generator.

Thanks.

 

[ceb58]

Okay, I think I found an answer, 445.13 Ampacity of the conductors from the generator terminals to the first distribution device shall not be less than 115 % of the nameplate current rating of the generator.

Thanks.

That is an incorrect answer. You stated the generator has OCP built in there for that rules out 445.13. The breaker is the first distribution device. Your conductors, between the gen. and disconnect, will have to be rated for the OCD on the generator 240.4 or 240.5 if you use flexible cord.

 

[AES1005]

Oh, ok thanks for the correction.