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Separately Derived Systems #84399
03/26/03 12:05 AM
03/26/03 12:05 AM
Carnak  Offline OP
Junior Member
Joined: Mar 2003
Posts: 5
Grand Cayman
Consider a commercial building with a three phase service and 100% generator back up.

If you use a 3 pole transfer switch, you don't break the neutral.

If you use a 4 pole switch, you break the neutral, add some extra grounding, and the system is now "Separately Derived".

When do you have to have the 4 pole transfer switch and the separately derived system?

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Re: Separately Derived Systems #84400
03/26/03 06:33 AM
03/26/03 06:33 AM
russ m  Offline
Joined: Feb 2003
Posts: 169
This same question is asked in the General Discussion Area.
Look for a post by wolfdog (backup generators)

I added this link to it. Just click it

[This message has been edited by russ m (edited 03-26-2003).]

Re: Separately Derived Systems #84401
03/26/03 06:45 AM
03/26/03 06:45 AM
russ m  Offline
Joined: Feb 2003
Posts: 169
I just went into the search section of this forum (ECN) and typed in transfer switch. There are alot of threads on this subject.


[This message has been edited by russ m (edited 03-26-2003).]


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