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Discussion Starter · #1 ·
I was going to put a 35kw generator in with a dual 200amp transfer switch. It turns out that the area has low gas pressure so I spoke to sales rep and 20kw can now run on 3.5wc and that is perfect the area will guarantee 4wc.

I'm planning on putting the 2 20kw generators in this week with 2 separate 200amp transfer switches. Each transfer switch will be feeding a 200amp panel. My question is will it be ok to have the 2 generators on the same neutral? I think it will but I'm starting to have 2nd thoughts. I don't know if it would somehow make a surge since it will be from 2 separate sources. But then I was thinking that there can be 2 house right next to each other off the same transformer and both have generators. The neutrals would be tied together at the pole so it would be the same thing. The reason this make me nervous is because I was doing a generator install on a split 400amp service and It was a CH panel with the ground strap so as normal I separated the grounds and neutrals. I removed the ground strap and turned the utility power on then I heard the transfer for the security system burn up and the furnace sounded like it was running slow. The short version is the opposite side neutral bars was getting the neutral from the back of the box and when I removed the strap there was no more neutral, it caused a surge some how and ended up costing me money in repairs to some appliances.
 

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Two 20's sucking off the same gas line with motor staring and I would think the gas issue will be a gas issue.
 

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Discussion Starter · #3 ·
The gas company has the available btu's I checked with them but the WC was low. They will change the meter for the 2 generatrs
 

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I was going to put a 35kw generator in with a dual 200amp transfer switch. It turns out that the area has low gas pressure so I spoke to sales rep and 20kw can now run on 3.5wc and that is perfect the area will guarantee 4wc.

The reason this make me nervous is because I was doing a generator install on a split 400amp service and It was a CH panel with the ground strap so as normal I separated the grounds and neutrals. I removed the ground strap and turned the utility power on then I heard the transfer for the security system burn up and the furnace sounded like it was running slow. The short version is the opposite side neutral bars was getting the neutral from the back of the box and when I removed the strap there was no more neutral, it caused a surge some how and ended up costing me money in repairs to some appliances.
Please explain this paragraph more in depth. I cannot picture how one panel gets a neutral through another panels mbj.
 

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Food for thought... Since your application isn't redundant or paralled gensets to a common bus - but two gensets feeding independant loads fed from a common utility source and I assume this is a three wire 120/240V system. As far as neutral current is concerned in this application, a common neutral could provide a path for circulating current between gensets if both are feeding loads simultanously. Depends on generator output voltage / waveform and the impedance of the sources, in this case the generators. Reactors are commonly used on paralleled Wye connected three phase generators for this reason.
 

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Discussion Starter · #6 ·
For my main question-
The service is a split 400amp service. There are 2 200 amp main panels. I have one generator with a 200amp transfer switch for one 200 amp panel. I have another generator for a 200amp panel with a 200 amp transfer switch. The neutrals will be together in the meter pan. Also I can not use one 20kw at this house. The home is 9000sf with 6 ac units. I will be shedding most of the AC units but just with the sf alone I will be more then a 20kw since a 20 is only 18 on NG.
 

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I've connected tons of multiple generator installations all with the same neutral, however in every case the gens were synched together and fed a common bus.

I don't see how connecting the neutrals together on gens feeding different panels would be a problem though. There would be no neutral current between the two gens as each one is supplying an independent load.

If you're using transfer switches that do not switch the neutral, you have no choice; all neutrals will be tied together anyway.
 
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