1 Generator, 3 ATS 1200a Service

[hurk27]

The generator is doing the whole load. The house has way too big of a service, I calculated it at a little of 400 amps. With load shedding a 48kw will do the whole house. I may just step their service down to 800a....

That would be possible if the panels weren't spread all over the finished home.....

48kw single phase is about 200 amps of supply, if the panels are spread all over the house how do you plan to load shed 200 amps of load from a 400 amp calculated load, by the way is that calculated load via article 220? or calculated demand load (the load will the generator see when the generator starts supplying current to the house)? the two are very different

This is what happens when a generator is not built into the electrical plans when a house is built, this must be a very large house to have that kind of load demand, and why in the world did they have a 1200 amp service installed if the load is only 400 amps???

I agree with the others you can not safely parallel 3 transfer switch's to supply one load, no two transfer switches will transfer at the exact time which will in-turn connect the generator back to the utility and an explosion will result.

About the only method is to put a transfer switch in each feeder of each panel the owners accept to be supplied, Generac does make systems for much larger services but they are going to be 3-phase systems under Generac's commercial/industrial line not under the home line.