Generator Docking Station Grounding

[Shujinko]

I have a project in design with a 4000A switchboard service main (normal side) and a 1000KW exterior generator with CB. All at 480Y/277V. The neutral and ground are bonded at the main switchboard and at the generator. All associated ATS's are 4-pole with a switched neutrals. Does my docking station have to be service entrance rated or non-service entrance rated? My biggest question is, when the docking station is connected to a temporary generator where does the neutral to ground connection come from? Do I need to establish another neutral to ground connection at the docking station for the times where the temporary generator is being used and the permanent generator is offline? Or does the docking station use the neutral to ground bond at the permanent generator when the temporary generator is connected to it?

 

[Strathead]

When a generator is a separately derived system, the bond to the enclosure/trailer, is considered the GEC. Whether it NEEDS to be a 4 pole system depends on whether it feeds a GFP breaker.

 

[Shujinko]

Yes, understood. In this case the generator is a separately dervied system, neu-grd bonded at the generator. We got GFP on the switchboard main since it's 4000A MCB & Ground fault alarm on the Generator. This is why we are using a 4-pole switched neutral system for the ATS's. But my real question is about the docking station when being used with a temporary generator.

 

[Strathead]

When a generator is a separately derived system, the bond to the enclosure/trailer, is considered the GEC. Whether it NEEDS to be a 4 pole system depends on whether it feeds a GFP breaker.

To clarify, my statement was not written correctly. When the portable generator is a separately derived system, it is required to be bonded to a grounding electrode system. Not sure how this is accomplished

 

[qcroanoke]

I have a project in design with a 4000A switchboard service main (normal side) and a 1000KW exterior generator with CB. All at 480Y/277V. The neutral and ground are bonded at the main switchboard and at the generator. All associated ATS's are 4-pole with a switched neutrals. Does my docking station have to be service entrance rated or non-service entrance rated? My biggest question is, when the docking station is connected to a temporary generator where does the neutral to ground connection come from? Do I need to establish another neutral to ground connection at the docking station for the times where the temporary generator is being used and the permanent generator is offline? Or does the docking station use the neutral to ground bond at the permanent generator when the temporary generator is connected to it?

I would think it would use whatever source the ATS is connected to since in a switched neutral both systems should be bonded.

 

[rlqdot]

I am not a generator expert, but why are you switching neutrals? If you use a solid neutral in the transfer switch(es), bonding neutral and GEC will be in the utility-connected service entrance equipment. I assume the generator-supplied panels and the transfer switch(es) are fed from a 1200 amp utility source or multiple smaller feeder breakers - the output of a 1000 KW genset is going to be right around 1200 amps 480Y277, so I doubt that it will be connected directly to the 4000 amp main busses. I very well may be missing something here, but the general description of the system doesn't seem to be complete.