Adding Genset to Existing Commercial Service

[deedo1124]

Client has a 4 wire service (480/277V) from a utility padmount feeding a main panel about 500' away. They plan to add a genset to back up this servive. They want the Electrical Contractor to cut into the main feeder outside by the transformer and install the xfer swith and genset adjacent to the xformer.
There is no ground conductor pulled with the main feeder and the neutral is bonded to ground at the main panel.

Question (1): In this scenario does the xfer switch now become the service entrance panel requiring a ground cable to be run to the main panel?

Question (2): Should xfer switch be a 3 or 4 pole.

Thanks for your time.

 

[ceb58]

Client has a 4 wire service (480/277V) from a utility padmount feeding a main panel about 500' away. They plan to add a genset to back up this servive. They want the Electrical Contractor to cut into the main feeder outside by the transformer and install the xfer swith and genset adjacent to the xformer.
There is no ground conductor pulled with the main feeder and the neutral is bonded to ground at the main panel.

Question (1): In this scenario does the xfer switch now become the service entrance panel requiring a ground cable to be run to the main panel?

Question (2): Should xfer switch be a 3 or 4 pole.

Thanks for your time.

What size is the service?

 

[deedo1124]

Service is 1600A

 

[ceb58]

Service is 1600A

Then you have GFP on the service, correct? If so then you will need a service disconnect before the ATS (unless it is service rated). The disconnect is where the N-G bond will take place and every thing after will be feeders. This is where it will change to a 5 wire system. If you do have GFP on the service you will need a 4 pole ATS, to switch the neutral, to prevent nuisance tripping. The generator would then be installed as a separately derived system.