Service with 3 pole transfer switch and generator.

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klm0824

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Location
Baton Rouge, LA
I have two cases. Both are municipal.
Case 1
  • Utility provided 480/277 at the weatherhead.
  • There is a main breaker between the utility and three pole transfer switch.
  • Grounded conductor (neutral) was brought into the service disconnect and bonded.
  • The generator (permanent) has circuit breaker.
  • Customer is saying we have to run the neutral from the generator to the service and bond there.
  • We have NO line to neutral loads. We ran a ground from the generator to the service.
Is the customer right about the neutral from the generator? If yes, can you please cite NEC?​

Case 2
  • Utility provided delta wye pad mount transformer with 470/277 on the secondary side. Meter is mounted at transformer.
  • There is a main breaker between the utility and three pole transfer switch.
  • The generator (permanent) has circuit breaker.
  • Do we have to run the neutral from the transformer if we have no line to neutral loads? We ran a ground, not a neutral.
  • Do we have to run a neutral from the generator to the service and bond there?
My backgound is industrial and I haven't had to deal with services much. We run 3 phase 3 wire systems all the time without a neutral...

This is what I am used to:
clip_image001.png
 
I have two cases. Both are municipal.
Case 1
  • Utility provided 480/277 at the weatherhead.
  • There is a main breaker between the utility and three pole transfer switch.
  • Grounded conductor (neutral) was brought into the service disconnect and bonded.
  • The generator (permanent) has circuit breaker.
  • Customer is saying we have to run the neutral from the generator to the service and bond there.
  • We have NO line to neutral loads. We ran a ground from the generator to the service.
Is the customer right about the neutral from the generator? If yes, can you please cite NEC?​


From the wording, I assume the TS does not switch the neutral. In that case, the generator is not a SDS and you
would not bond the neutral at the generator. You would run a grounding conductor to provide a return path. Withj no neutral load, I see no need for the neutral to leave the generator.

Case 2
  • Utility provided delta wye pad mount transformer with 470/277 on the secondary side. Meter is mounted at transformer.
  • There is a main breaker between the utility and three pole transfer switch.
  • The generator (permanent) has circuit breaker.
  • Do we have to run the neutral from the transformer if we have no line to neutral loads? We ran a ground, not a neutral.
  • Do we have to run a neutral from the generator to the service and bond there?
My backgound is industrial and I haven't had to deal with services much. We run 3 phase 3 wire systems all the time without a neutral...

This is what I am used to:
View attachment 6901

To some degree we are playing semantics. If it's a utility transformer with a wye secondary, you are required to bring the grounded conductor to the service disconnect {250.24(C)}. You do not need a grounding conductor, so if the one you ran is sided per 250.66 some identifying and terminating may solve the problem
 
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