house generator for 400 amp house

A customer bought a 22 kW generator with automatic transfer switch. I've installed 200 amp generator kits but not 400 (320 amp here). I'm not sure how to do that with two panels. Will the transfer switch have double lugs ? The last 200 amp generator kit I did, I pretty sure I placed the transfer switch between the meter and panel. Thanks !
 

brantmacga

Señor Member
Location
Georgia
Occupation
Electrical Monke
The 400A ATS have dual cable rated lugs, the 200A do not.

Would be easier to do two switches, the problem is going to be getting another switch right now. Every manufacturer is experiencing severe delays on components.

What brand is the generator ?


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Knuckle Dragger

Master Electrician Electrical Contractor 01752
Location
Marlborough, Massachusetts USA
Occupation
Electrical Contractor
The last service rated 400 ATS I installed was over 20 years ago. It was a Kohler the generator I believe was 22K. If it's a 400 amp ATS then it should come with duel lugs. I don't recall any issues tying it in. It didn't have much for load management except a few dry contacts that opened when the ATS initiated.
Yes you do place it between the meter and the panels if it is service rated.

I've been struggling to find a 400 service rated ATS with load management options lately.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Electrical Monke
The last service rated 400 ATS I installed was over 20 years ago. It was a Kohler the generator I believe was 22K. If it's a 400 amp ATS then it should come with duel lugs. I don't recall any issues tying it in. It didn't have much for load management except a few dry contacts that opened when the ATS initiated.
Yes you do place it between the meter and the panels if it is service rated.

I've been struggling to find a 400 service rated ATS with load management options lately.
Generac makes a 400A SER ATS with four load shed contacts.

Eaton also makes one with two load shed contacts.

The generac smart management modules use frequency based load shedding and will work with anything.


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LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
When I compared, the 2x 200a ATS setup was much cheaper, as well as easier to install in an existing 2x 200a panel service.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Electrical Monke
When I compared, the 2x 200a ATS setup was much cheaper, as well as easier to install in an existing 2x 200a panel service.
That is correct. I think my cost on the 400A switch is around $2k, and my cost on the 200A switch is $700.


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augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Almost seems a waste with a 22k generator even with load shedding.
Would it not be reasonable to place the "non-essential" loads in one of your panels and use the other for priority loads.
Even then you will have to load shed but not a severely.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Agreed. Unless the desire is to be able to run "everything," my preference is to re-distribute loads between the two panels, and power only one from the genny.
 

Knuckle Dragger

Master Electrician Electrical Contractor 01752
Location
Marlborough, Massachusetts USA
Occupation
Electrical Contractor
Agreed. Unless the desire is to be able to run "everything," my preference is to re-distribute loads between the two panels, and power only one from the genny.
On the higher-end homes and even not so high-end homes my customers want to have the option to run the whole house.
I tell them that there is great responsibly that comes with that option and that their loads will have to be managed manually or automatically.

I've never installed a tandums ATS. I assume there is a relay or initiates them simultaneously.
Any down sides with the tamdum set ups?

I have a few generator jobs coming up. On one job the space is a little tight for all the gear the gear that's one of the reasons for the single 400ATS.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
I've never installed a tandums ATS. I assume there is a relay or initiates them simultaneously.
Any down sides with the tamdum set ups?
Two Generac ATSs connect together in a master/slave configuration, so one controls both.

No downside as long as your feeder splits correctly, and your generator has the ampacity.
 
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