# Arc Flash / Blast On The Neutral Side Of A Large Generator



## brian john (Mar 11, 2007)

Lone Crapshooter said:


> We have a generator and the neutral is connected to ground through a air breaker and a grounding resistor to ground. The output of the generator is 13.2 KV. There is a second generator but the 2 machines are not tied directly with a synchronizing bus . With the the generator shutdown is there a arc blast / flash potential when operating the the neutral breaker.
> I say no but I was told there was but not given a explanation why.


Generator is off, not tied to the other generator and not tied to the utility bus?

I’d have to think no. But this is based on my opinion.


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## RIVETER (Sep 26, 2009)

Lone Crapshooter said:


> We have a generator and the neutral is connected to ground through a air breaker and a grounding resistor to ground. The output of the generator is 13.2 KV. There is a second generator but the 2 machines are not tied directly with a synchronizing bus . With the the generator shutdown is there a arc blast / flash potential when operating the the neutral breaker.
> I say no but I was told there was but not given a explanation why.


Maybe something new to me but is this a resistive grounding system? Is it a 24/7 I square R loss type of system?


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## Big John (May 23, 2010)

I've only seen neutral breakers on a system where multiple generators were set up to be paralleled, but only one genny would be grounded in order to reduce circulating currents.

Since you mention having more than one generator, it sounds like your setup might be a similar design. Is it an actual circuit breaker or just an isolator?

If you can confirm that neutral point isn't being used by any other generators, I agree you should be able to open that breaker. 

-John


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