# Generator question



## backstay (Feb 3, 2011)

Surge03 said:


> Question, I need help sizing a generator for emergency power. There are 5 separate buildings being fed off one switch gear but they only want the main building to have emergency power. I have 3 panels feeding lights, etc so for example can I get a 400 generator and parallel feed 3 ATS switches for 3 different panels? Or how would you guys do this?


You don't have a single feed to a disco? I know you don't have to. I don't see a problem with three ATS' with only one controlling the Benny. But wouldn't single feeding one and breaking out to the three panels be cheaper?


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## Surge03 (Sep 23, 2012)

backstay said:


> You don't have a single feed to a disco? I know you don't have to. I don't see a problem with three ATS' with only one controlling the Benny. But wouldn't single feeding one and breaking out to the three panels be cheaper?


I have to see if I can fit a bigger size breaker in that style of gear,I would need to fit at least a 400 amp 3 pole than single feeding one ATS and branching out.


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## mbednarik (Oct 10, 2011)

The main building has 3 different feeds?


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## micromind (Aug 11, 2007)

Any number of transfer switches can be used with one or more gens. 

One of the local casinos around here has 17 xfer switches and 4 gens. Any xfer switch will start all 4 gens and they'll synch together and power whatever loads have a dead utility.


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## donaldelectrician (Sep 30, 2010)

Surge03 said:


> I have to see if I can fit a bigger size breaker in that style of gear,I would need to fit at least a 400 amp 3 pole than single feeding one ATS and branching out.[/QUOT
> 
> 
> 
> ...


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## SdCountySparky (Aug 6, 2014)

kilowatt = amp × volt / 1000. That's how you'll size your generator and ATS. You'll need to intercept the feed powering the main building with an ATS. What is the buildings incoming voltage multiply that by 400 (amps) and divide that by 1000 and that'll give you the KW you are looking for.


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## SdCountySparky (Aug 6, 2014)

You size your generator in kilowatts not amps.


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