# One Generator, 2 transfer switches



## HARRY304E

kbsparky said:


> I have a job where there is an existing 175 kVA generator, connected to a 100 Amp transfer switch.
> 
> They are adding a second transfer switch in another part of the building which will be connected the same generator. This one will be a 200 Amp unit.
> 
> Since each transfer switch's normal utility power is fed from a different set of transformers, we need to be able to start the generator from either transfer switch.
> 
> I figure that simply connecting the 2-wire remote start lines together in parallel should do the trick.
> 
> Is this a feasible solution?
> 
> We are dealing with GENERAC equipment here. Not the cheap residential stuff, but the large commercial units. 480 Volts 3 phase.


I agree that should work just fine.:thumbsup:


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## nolabama

I have a two transfer switch generator. It's stupid. Why do you need to do this. Cause ones already there? That's why mine ended up thataway


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## socalelect

Should not be a issue we have a customer that has a giant Kohler gen with 4 or 5 transfer switches attached, it can be a pain in the ass at times when there is a problem trying to figure out which switch is causing the problems, don't the generals have the transfer stuff in the gen?


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## nolabama

Oh I re read this it's powering two separate services. Mines powering one with one transfer upstream of the other , which is stupid. Yours sounds like a responsible application.


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## kbsparky

Looks like you read it again.

Yup, 2 different services


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## kbsparky

socalelect said:


> ... don't the generals have the transfer stuff in the gen?


Nope. Maybe in the cheap-junk residential line, but not for the large commercial stuff ...


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## BBQ

kbsparky said:


> Nope. Maybe in the cheap-junk residential line, but not for the large commercial stuff ...


It depends on what you order.

Generac makes large commercial units that do indeed have the brains in the generator and just a data connection to the transfer switch. Crappy arraignment in my opinion.


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## McClary’s Electrical

Just did one today.





























Wood was wrotten









Added some plywood


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## micromind

One of the local casinos around here has 4 gens, 17 transfer switches and two services. 

The gen start contacts of all xfer switches are paralleled, so if one or more of the xfer switches calls for gen power, all 4 units start and synch together (most of the time anyway.....)

There's no limit to how many xfer switches you can have. If all start contacts are paralleled, the gen will start and depending on how the priorities are set up, only those with dead utility will go to gen power.


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## kbsparky

mcclary's electrical said:


> Just did one today...


Think you could orient those pix so my neck don't get crooked? :blink:


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## glen1971

It should work fine.. The only question I'd have is, are either of the transfer switches a bumpless one, that would require synchronizing before going offline? If so I'm not sure how the gen would go offline once power was restored if one was "fighting" the other one to synch.. Just a thought, but if they are break-before-make switches you should be good.


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## brian john

kbsparky said:


> We are dealing with GENERAC equipment here. Not the cheap residential stuff, but the large commercial units. 480 Volts 3 phase.


Here I fixed it for you

*We are dealing with a CHEAP GENERAC equipment here. Not the cheap residential stuff, but the large CHEAP commercial units. 480 Volts 3 phase*


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## socalelect

brian john said:


> Here I fixed it for you
> 
> We are dealing with a CHEAP GENERAC equipment here. Not the cheap residential stuff, but the large CHEAP commercial units. 480 Volts 3 phase


Good one brian :thumbsup:


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## kbsparky

I don't know what they paid for that large unit (about the size of a small car), but I bet it wasn't cheap!


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## Mshea

nolabama said:


> I have a two transfer switch generator. It's stupid. Why do you need to do this. Cause ones already there? That's why mine ended up thataway


Up here in Canada land you are not allowed to put non life safety systems on the same transfer switch as emergency loads.
It is possible to use a single generator to back up non essential systems like computers and other non life safety loads, A transfer switch for the emergency loads (lighting, fire alarm, Elevator returns, fire fans, etc. A third transfer switch could also be required for a fire pump which must be fed from it's own transfer switch.
Here it can be building code.


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## socalelect

kbsparky said:


> I don't know what they paid for that large unit (about the size of a small car), but I bet it wasn't cheap!


From what I have seen size compared for size generac is usually the cheapest, we prefer Kohler for the larger units


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