ONE GEN TWO BLDGS

[dereckbc]

Re: ONE GEN TWO BLDGS

Has anyone brought up the idea of using isolation transformers?

 

[iwire]

Re: ONE GEN TWO BLDGS

Originally posted by don_resqcapt19:
Bob,

Don I had assumed a service entrance transfer switch which in that case I did not see a violation.

Even if they are service rated transfer switches the grounded conductor from the transfer switch to the generator and then to the other transfer switch would create the violation.
Don

Don I do not think we are talking about the same installation.

I am picturing a service rated transfer switch that is the buildings service disconect. In that case these multiple paths are on the supply side of the service disconnect and the NEC does not prohibit multiple grounding on that side.

 

[don_resqcapt19]

Re: ONE GEN TWO BLDGS

Bob,

I am picturing a service rated transfer switch that is the buildings service disconect. In that case these multiple paths are on the supply side of the service disconnect and the NEC does not prohibit multiple grounding on that side.

So am I. While the transfer switch may be the service disconnect, the conductors that leave the transfer switch and go to the generator are, in my opinion, on the load side of the transfer switch and therefore a violation.
Don

 

[iwire]

Re: ONE GEN TWO BLDGS

Originally posted by don_resqcapt19:
So am I. While the transfer switch may be the service disconnect, the conductors that leave the transfer switch and go to the generator are, in my opinion, on the load side of the transfer switch and therefore a violation.
Don

Don I can not agree to that, the conductors do not leave the transfer switch and go to the generator.

The conductors leave the generator and supply the transfer switch.

I bet any transfer switch we look at will refer to those conductors as emergency supply conductors.

But it is certainly a mess as they are not service conductors.

I agree from design stand point that this installation should use a switched neutral required or not.

 

[don_resqcapt19]

Re: ONE GEN TWO BLDGS

Bob,

The conductors leave the generator and supply the transfer switch.

While they do supply the transfer switch, they are still on the load side of the service disconnect.
Don

 

[iwire]

Re: ONE GEN TWO BLDGS

Originally posted by don_resqcapt19:
Bob,

The conductors leave the generator and supply the transfer switch.

While they do supply the transfer switch, they are still on the load side of the service disconnect.
Don

I can not see how that is possible.

 

[George Stolz]

Re: ONE GEN TWO BLDGS

Isn't a generator effectively considered an appliance (in terms of bonding) until it achieves SDS status?

 

[ccjersey]

Re: ONE GEN TWO BLDGS

It looks like the important thing is where the transfer switch is installed in relation to the neutral-ground bond at the main panel.

If the transfer switch is on the utility side of the main panel with the bond, any parallel path through the generator conductors would be the second one on the utility side. I believe it is common for the utility to bond primary and secondary neutral at the transformer so there are neutral paths between service drops all along the line.

With a smaller transfer switch fed out of the main panel, (on the customer side of the main panel with the N-G bond), there would be a problem.