AUEngineer
I recently inherited a Carrier model ASPAX1CCA015 (re-stickered Generac model 4390-3) generator. Generator has always had its annual maintenance, performs perfectly, and is in good shape. I will hopefully be installing this unit within the next few weeks--it will be running on natural gas.

Since the generator is not big enough to run all the connected loads in my home, I'll need a load management ATS to meet NEC 702 requirements.

I have 200 amp service from the electric company. I'd like to introduce a 200A service entrance rated transfer switch between the meter and my current 240V load center panel for the house.

[B][U]Can I use a new Generac RXSW200A3 ATS with my model 4390-3?[/U][/B] I have two smaller 2-ton AC units this switch can handle load shedding for out of the box. I'd think that the 12V signal on 23 and 194 from the generator would allow this newest model ATS to transfer power and perform properly? [B]I am not sure if there are other concerns, however?[/B]

If I upgrade the generator in the future, depending on how far down the road that is, this RXS switch would work well with a new Nexus-controlled Generac generator. Considering a future upgrade, I'd go ahead and run #3 copper for power, and extra conductors for T1 and 0 (though I wouldn't need these conductors for the old generator).

[B]If the RXS series is not compatible with my old generator, any suggestions of what to do?[/B]

I'll hire a qualified electrician to do the hard stuff, and have the job inspected by the county. But since used equipment is involved, I want to understand, fully, what I'm doing on the front end.

Thanks for any feedback/advice from the experts.
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Brian Baughman
Yes, the ATS will work with the generator. Any Generac RTG, RTS, RXG, or RXS transfer switch would work. I do recommend installing all of the necessary control conductors (N1, N2, T1, 0,23, 194), that way you are covered when the generator has to be replaced.
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AUEngineer
I have seen the older Generac "HS type" ATS's that have a toggle switch and relay mounted in them. How do those older transfer switches work with this relay, versus the newer Generac switches that do not (appear anyway) to have a relay mounted within them?
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