Supplying two ATS's from one generator

[JoeNorm]

I am setting up a residential 320amp meter base to receive a generator in the future. Residence has a 400amp meter/main. I plan to mount two 200 amp ATS's at the meter main that correlate to each 200 amp breaker in the enclosure.

Do generators in the 50KW range generally have lugs to accommodate parallel runs of wiring? This will be a Kohler propane if it ever gets installed.

See anything wrong with this plan?

 

[jaggedben]

I recall some other threads raising the point that in this situation you may need 3-pole ATS to avoid a potentially problematic parallel neutral path through the generator.

 

[Seven-Delta-FortyOne]

I run one set of conductors to a gutter, and split from there to the two ATS.

The other option is Polaris connectors in the first ATS.

Both options in my opinion are easier than pulling two sets from the genny.

 

[Birken Vogt]

If you are running a single 200 amp generator, why does the place need 2 200 amp mains?

We retrofit a lot of places like this, we generally find that all house loads can easily calc out below 200 amps, and install a single 200 amp ATS and leave the other 200A feeder unconnected, or connected to something like solar, or landscape/Christmas lighting.

 

[LarryFine]

I usually recommend one genny panel and one non-genny panel.

Costs less, simpler to wire, and less load-shedding worries.

 

[JoeNorm]

This place I would describe as more of a compound. One 200 feeds the main house, pool, and "guest house." The other 200 goes off to feed the well water system, garage, and maybe another outbuilding.

If it wasn't for the water system being on the other 200 I would have just used one ATS on one of the 200's

 

[Birken Vogt]

This place I would describe as more of a compound. One 200 feeds the main house, pool, and "guest house." The other 200 goes off to feed the well water system, garage, and maybe another outbuilding.

If it wasn't for the water system being on the other 200 I would have just used one ATS on one of the 200's

Last one of these I did I just put the other 200 amp feed on a 125 out of the transfer switch and called it good. (The loads calc much less than 125 even)

Again, if you only have a 200 amp genset, why do you need more than one 200 amp feed and 200 amp transfer switch?

 

[jaggedben]

If it wasn't for the water system being on the other 200 I would have just used one ATS on one of the 200's

So the well water system uses 200A?

(Okay, I'm being facetious, but my point is if you don't do a load calc or check usage, how do you actually know?)

 

[JoeNorm]

Last one of these I did I just put the other 200 amp feed on a 125 out of the transfer switch and called it good. (The loads calc much less than 125 even)

Again, if you only have a 200 amp genset, why do you need more than one 200 amp feed and 200 amp transfer switch?

The Gen is not purchased yet, may be bigger than 200 amp feed if we find it necessary

 

[JoeNorm]

So the well water system uses 200A?

(Okay, I'm being facetious, but my point is if you don't do a load calc or check usage, how do you actually know?)

Of course not, but it's fed hundreds of feet away off of a separate 200 amp feed.
The idea is we are setting up the residence to receive a generator in the future, load studies will be done in the meantime. But I still don't see how i could avoid two ATS's

 

[Birken Vogt]

You do like we always do even on retrofits, feed everything off one 200 amp feed and transfer switch, and ignore the other one or reserve it for future use.

It could be done with 2 switches, but I have not found it necessary for the ordinary 4000 sq ft house/estate. They don't really take or calc that much power, so it becomes easier to just consolidate loads on a single switch.

The only gens I have installed over 200 amps have been on commercial where there was a singe 400 amp feed.

 

[LarryFine]

If it wasn't for the water system being on the other 200 I would have just used one ATS on one of the 200's

Is there anything that can be done about this now?

 

[JoeNorm]

Is there anything that can be done about this now?

Anything I did seems like it would be much more expensive than adding a second ATS.

 

[LarryFine]

Then you're going to have to deal with load-shedding.

 

[JoeNorm]

Then you're going to have to deal with load-shedding.

Why? The plan is to wait until the house is lived in for a couple years and study the demand data. At that point we size the gen accordingly. Am I missing something?

 

[LarryFine]

Why? The plan is to wait until the house is lived in for a couple years and study the demand data. At that point we size the gen accordingly. Am I missing something?

Only telling us this stuff.

I think you'll have to use "what could be left on" rather than "what is usually left on" in your calcs.

 

[marmathsen]

I'm surprised to see so much encouragement toward reworking circuits or adding a sub panel etc over adding a second ATS. I can easily picture some scenarios where it would be a lot less work to just add a second ATS to feed the second service panel. Is there something intrinsically wrong with that? It some major complication that the OP and I aren't thinking about?

Rob G - Seattle

 

[LarryFine]

Is there something intrinsically wrong with that? It some major complication that the OP and I aren't thinking about?

No, I'm just cheap.

 

[marmathsen]

No, I'm just cheap.

I can respect that!

Rob G - Seattle

 

[Knuckle Dragger]

I've installed tandem 200amp ATS with a common trip relay on Cummings products a couple of times. You shouldn't have a problem with it. I have heard that Kohler is a better product overall.