multi sds grounding & OCPD

[peterelec]

I have a building that is powered from an outside transformer. The building will also be backed up by a generator, for all power, via a 4 pole transfer switch. The transformer, generator and transfer switch are located outdoors. Questions, 1) will the transfer switch require OCPD for the transformer feed into it & 2) where should the N-G bond take place, at the transfer switch or inside at the Main switch in the switchboard. Thank you in adavnce for your responses.

 

[mc5w]

Re: multi sds grounding & OCPD

Question 1: Yes. You have to have a service switch with overcurrent protection ahead of the transfer switch.

Question 2: The normal power has to have the ground bond at or ahead of the service switch. If your service switch switches the neutral then there has to be another bond and grounding electrode at the generator or the the generator circuit breaker.

 

[mc5w]

Re: multi sds grounding & OCPD

If your generator is anywhere near the building then the generator also has to use the same grounding electrodes as the service and this bonding jumper has to be in addition to the equipment ground running from the generator to the transfer switch.