250.30A Question

[ceb58]

We have contractors installing some generators for us at work. These systems are being installed as SDS (switching the neutral in the ATS). The inspector is allowing the bonding of the neutral and GEC (from underground halo system) in the fusible disconnect at the building instead of at the breaker on the gen.
My question is after reading 250.30 A and getting a headache. They are bonding the frame of the gen. to the underground halo system but should there also be a system bonding jumper ran back from the disco. and bond to the frame of the gen. also?

 

[S'mise]

I agree. The first disconnecting means is at the Generator so why is it bonded at the building?
I would think no to your question. A bonding jumper running back from the disco would cause paralell paths. (bonded at both places)

 

[ActionDave]

The inspector may be ignoring the breaker on the generator and defining your first disconnect as the fusible disconnect on the building. If so then I see the GEC connection going there only and no connection to the halo at the generator.

You would then need an Equipment Bonding Jumper to the generator not a System Bonding Jumper.

 

[ceb58]

The inspector may be ignoring the breaker on the generator and defining your first disconnect as the fusible disconnect on the building. If so then I see the GEC connection going there only and no connection to the halo at the generator.

You would then need an Equipment Bonding Jumper to the generator not a System Bonding Jumper.

The inspectors reasoning was they are considering the generator as the "source" and are going ether way. Bond at the breaker on the gen. (my preference) or bond at the disconnect. Seems it is easier to do the bonding in the disco. So they would need an EGC ran back to the gen and bonded to the frame only. Or would the frame bonded to the halo be sufficient?

 

[ActionDave]

My opinion is EGC back to the generator frame, but it is called an Equipment Bonding Jumper and is size from 250.66.

Is this at a cell site? Where is the disco in relation to the transfer switch?

We had a similar arrangement setting up transfer switches for sewer lifts all around town, but the generator was portable.

 

[ceb58]

My opinion is EGC back to the generator frame, but it is called an Equipment Bonding Jumper and is size from 250.66.

Is this at a cell site? Where is the disco in relation to the transfer switch?

We had a similar arrangement setting up transfer switches for sewer lifts all around town, but the generator was portable.

Not a cell site but a communication site. The gen. disco is located on the outside wall of the building with the ATS inside

 

[ActionDave]

Cool. We have been doing a lot of work on cell sites recently with the digital change over and the merger between Alltel and Verizion.

 

[KingDavid]

It seems to be quite common that even large generators are considered 'temporary' by customers. I have an inspector that agrees, classifying the gens as 'temp', ask that the bonding be done at the first disconnect and not the gens.