NOT switching the neutral

[ath123]

I have a 3000A grounded wye service with main breaker, GFP and 3 pole ATS. The generator neutral and ground are not bonded together and are tied to the respective buses of the swithcboard. Is this a code violation?

 

[WoodrowJWeen]

No, this is perfectly legal.

 

[ath123]

So when running the plant on the generator, we have no GFP. If the GFP trips the utility main, the generator will not sense normal power when restored. Is this correct? Do you see any other issues with this scenario?

 

[dpc]

Ground fault protection will depend on the location of the ground fault detection versus the generator connections to the bus.

The generator breaker can also have GFP.

If your local 480 V main breaker trips, you should not be trying to re-energize from the generator, since you could be closing in to a bus fault. You need sense loss of utility voltage ahead of the main breaker.

 

[rbulsara]

In your situation, where generator is not-separately grounded, the generator's neutral must be solidly connceted to the service neutral. Then 3P ATS is OK, and generator is also grounded (through the service neutral).

If the two neutrals are not interconnected (may be because the load does not need a neutral) then you must ground the generator neutral at the generator end.

 

[alehman]

If you need GFP at the generator circuit breaker, you will need to install the neutral CT downstream of the ATS.