Trouble With 3-Phase Generator Feeder.

[Seven-Delta-FortyOne]

I kind of feel like an idiot, but I have a lot of divergent projects going on, and this one is giving me a headache.

If anyone would like to shed some light, I would be grateful.

I have a site with no grid power.

There is a 45kVa generator. 26kW at single phase.

I wired it for single phase, now he wants it changed over to 3 phase.

There is a 90 Amp main breaker on the generator.

26kW at 240 Volts is 108 Amps.

45kW at 208 Volts is 125 Amps (roughly).

First, why the 90 Amp breaker?

2, do I size the feeder for 125 Amps, or 90 Amps?

Can I size it as a 90 Amp service, because the "service disconnect" is on the generator?

I'll need to size the conductors for 125%, as it will have continuous loads.

 

[don_resqcapt19]

90 amp conductors on the load side of the breaker are fine.
But, like you, i wonder why the breaker is 90 amps for that unit.

 

[Seven-Delta-FortyOne]

Thanks. That's what I thought, then started to second guess because of 445.13(a). Says to size them to the nameplate current rating.

For the little portables when I do transfer equipment, I always size to the breakers.

Then the 90 Amp breaker threw me off. Generator is an SPG, evidently made by a company called Allman. I've never dealt with these before, it appears to be a Chinese manufacturer.

 

[don_resqcapt19]

Thanks. That's what I thought, then started to second guess because of 445.13(a). Says to size them to the nameplate current rating.

For the little portables when I do transfer equipment, I always size to the breakers.

Then the 90 Amp breaker threw me off. Generator is an SPG, evidently made by a company called Allman. I've never dealt with these before, it appears to be a Chinese manufacturer.

Nothing in 445 applies to the conductors on the load side of the first OCPD after the generator windings.