Standby generator wire sizing

[Birken Vogt]

Are you using 310.12 to size this feeder as it supplies the entirety of the home?

I ask because table 310.16 gives #2 AL an ampacity of 90amps.

I never thought of using 310.12 in a generator scenario and am curious if this is compliant.

No reason it should not be compliant. But most jobs we do have load shedding and are actually fed with a 200 amp utility service. With load shedding I feel the conductors could be running close to their rating for longer and therefore 310.12 would not really apply.

 

[LarryFine]

Feeder conductors are never required to be larger than the service conductors.

I imagine the same rule applies even when there are no service conductors.

 

[jaggedben]

I think you can use 310.12 if you're backing up the whole home with the same size feeder as the service. Otherwise I don't think you can.