Neutral switching in transfer switch

[magoo]

I don't know if this subject has been brought up before, but I recently had an inspector question me on whether or not the neutral was required to be switched on an automatic transfer switch. The application is: 480v, 100a, 3 phase automatic bus transfer switch from utility supply to emergency generator in an Oregon State Forestry office building. I'm not involved in this project at all, so I don't know what kind of load will be on the generator if that even makes any difference. Any code references would be appreciated.

(oops, looks like I used the wrong forum)

[ March 28, 2003, 11:56 PM: Message edited by: magoo ]

 

[bennie]

Re: Neutral switching in transfer switch

Hello Magoo: The job specs. may require that the premises wiring be a separately derived system, during a power outage.

The neutral/ground must be switched.

[ March 29, 2003, 04:58 AM: Message edited by: bennie ]

 

[Ed MacLaren]

Re: Neutral switching in transfer switch

In order to be code compliant, the grounded (neutral) conductor is only required to be switched when the generator winding wye-point (neutral)is bonded to the generator frame.

See responses, including diagrams, in your other thread.
http://www.mikeholt.com/codeforum/ultimatebb.php?ubb=get_topic;f=11;t=000361

Ed