No main breaker on 2MW Generator

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wylfer

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Hello everyone, I'm trying to find out what considerations should be taken for not having a main breaker on a generator. The customer plans to bring cables directly from the generator to two individual feeders to supply two separate circuits. Would be allowed according the NEC/CSA code? I have not been able to find much information about this type of configuration. I would think having the cables coming from the generator to a common bus and then split off to two breakers would be more acceptable, but may need additional consideration for the neutral in case there is a fault on one of the circuits.

Any thoughts would be greatly appreciated. Thanks for taking the time to read this.
 
Even for a 2 MW generator I would think it would need to be protected from overload by “inherent design, circuit breakers, fuses, or other identified overcurrent protective means.”
 
NEC code. That's correct, it's a 2MW generator feeding two separate power houses at 480VAC. The protection would be provided by two 1600amp breakers instead one main 3200amp breaker.
 
parrygill said:
NEC code. That's correct, it's a 2MW generator feeding two separate power houses at 480VAC. The protection would be provided by two 1600amp breakers instead one main 3200amp breaker.
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I think you have an issue with 445.13(A). The way I read that, each feeder will have to have an ampacity of 115% of the nameplate rating of the generator.
 
don_resqcapt19 said:
I think you have an issue with 445.13(A). The way I read that, each feeder will have to have an ampacity of 115% of the nameplate rating of the generator.
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Don; The 2017 NEC does have one exception, and there is also 445.13(B), just depending on the design of the generator.

So I don't think we can know for sure without knowing more about the generator.
 
steve66 said:
Don; The 2017 NEC does have one exception, and there is also 445.13(B), just depending on the design of the generator.

So I don't think we can know for sure without knowing more about the generator.
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Ok, so then we have to look to the tap rules.
 
I would bet you could get the generator with two 1600A circuit breakers instead of a single 3200A circuit breaker and not have to worry about tap rules or the like.
 
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