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#35973 03/25/04 09:57 PM
Joined: Dec 2001
Posts: 201
ayrton Offline OP
I have a building w/ a 1 phase 400a service. CT Cab w/ 250 feeders which are tapped to 4/0 through a meter socket and into a 400a Main breaker MDP. Understanding, that the building is only reading about 180a. under load.
2nd I have a 200a 240v 3 phase service. Have a 70a 3p hvac unit I need to power on a generator along with the entire single phase load. Now my associate who has a generator business whom I have worked w/ before and is a friend, says he see's this all the time and sparky's he hass used will wire a back up system this way.
Meaning, Use a three phase generator, one 3phase Auto transfer switch and power both systems. I do not see in the code where this is prohibited, but it doesn't seem right. Can someone shed some light and give advise???

#35974 03/26/04 03:25 PM
Joined: Dec 2001
Posts: 201
ayrton Offline OP

#35975 03/26/04 08:09 PM
Joined: Mar 2002
Posts: 582
Ron Offline
Safe to assume that there are no 120V loads?
I don't follow, is there two buildings or one building with two services.
Will this be an Article 700, 701 or 702 type generator.
What will the load side of the ATS serves, a distribution board?

[This message has been edited by Ron (edited 03-26-2004).]

#35976 03/26/04 08:13 PM
Joined: Dec 2001
Posts: 201
ayrton Offline OP
This is one building Ron. I assume you know this A typical a 1phase service and a 3 phase to one building. The significnat load IS 120v. Mainly lighting and office receptacles. This would be a pad mount Onin generator (diesel with automatic transfer switch. There is aprox 180A of load on single phase service. There is a seperate Disconnect off of the 3 phase service which feeds an HVAC unit (70a)
I am not seeing how I can feed both services with the generator. What if they are fed from seperate xfmrs on the street. This is in the city and I am not certain where supply is from

[This message has been edited by ayrton (edited 03-26-2004).]

#35977 03/26/04 09:53 PM
Joined: Nov 2000
Posts: 2,148
If there are two services, then you have to use two transfer switches. There is no other way.


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