Bonded neutral generator

[Dsg319]

At a job site where we plan to have grid power (single phase) and also have a back up generator, it is a bonded neutral genset.

So they will have a neutral and EGC bond at the service main disconnect and also at the generator.

And the transfer switch we received has an isolated neutral of course. But does not switch the neutral. I always that the neutral need switched when you have a bonded genset? Am I write or wrong.

Because the way I see it is with a bonded genset and non switched neutral in the ATS is when using generator power. current can travel on neutral from ATS back to service disconnect EGC bond than flow on all the different paths bonded including EGC all the way back to the genset.

little info- 240/120 single phase 200amp service and genset.

 

[ptonsparky]

I believe you are correct about the transfer switch. You may be able to isolate the bond in the genset. I’ve never done it.

 

[Dsg319]

I believe you are correct about the transfer switch. You may be able to isolate the bond in the genset. I’ve never done it.

I believe that also that the genset neutral needs to be floating/isolated since the ATS does not switch neutral. For the reason of objectionable current.

 

[Dsg319]

The yellow is where I could see neutral current. On EGC and all bonded conductive parts. (Although drawing does not show generator bond as I’m just using this as a reference)

 

[LarryFine]

Either both sources are bonded and you switch the neutral, or both sources are not bonded and you don't switch the neutral.

If you have one bonded and one non-bonded source, one must be modified, and then switch or don't switch the neutral to suit.

 

[Dsg319]

Either both sources are bonded and you switch the neutral, or both sources are not bonded and you don't switch the neutral.

If you have one bonded and one non-bonded source, one must be modified, and then switch or don't switch the neutral to suit.

That’s what I was thinking. I don’t have a lot experience with generators and ATS but have been studying them for a bit and wanted to make sure I was correct.

 

[Dsg319]

Iv

Either both sources are bonded and you switch the neutral, or both sources are not bonded and you don't switch the neutral.

If you have one bonded and one non-bonded source, one must be modified, and then switch or don't switch the neutral to suit.

Ive talked and both showed images that the neutral needs to be unbonded at the genset. But I am just a worker bee so I can only do so much. It got terminated while a was gone one day for doctors appointment and came back to find it bonded.

I know nothing dramatically might not happen right off the bat, but I know it will cause objectionable current on all bonded equipment and steel. But what are some others hazards it can present?