A 1000KW generator is permanently installed for whole building backup to a 277/480V service for a large grocery store. The Utility is providing 12,470V to the transformer primary. The transformer is owned by the customer. There is a 1600 ampere three pole, solid neutral transfer switch located outside with the generator and transformer in close proximity. The building Main Distribution Panel is located inside the building 75 feet away from the transfer switch feeding it.
Q1) Since the transfer switch is 3 pole, should the generator frame and neutral NOT be grounded, letting the main service bonding establish the ground for both the Utility service and the generator service (hence the generator will not be considered a separately derived source)?
Q2) A breaker with GFP is installed at the transformer secondary protecting the feed to the transfer switch. A breaker w/o GFP is installed at the generator protecting its feed to the transfer switch. There is a main breaker with GFP in the MDP 100 feet away from the transfer switch. With this arrangement, should the main bonding jumper be established at the MDP? If so, should the transformer secondary neutral be bonded to its frame as well (again, this is an owner furnished transformer, Utility fed primary)?
Q1) Since the transfer switch is 3 pole, should the generator frame and neutral NOT be grounded, letting the main service bonding establish the ground for both the Utility service and the generator service (hence the generator will not be considered a separately derived source)?
Q2) A breaker with GFP is installed at the transformer secondary protecting the feed to the transfer switch. A breaker w/o GFP is installed at the generator protecting its feed to the transfer switch. There is a main breaker with GFP in the MDP 100 feet away from the transfer switch. With this arrangement, should the main bonding jumper be established at the MDP? If so, should the transformer secondary neutral be bonded to its frame as well (again, this is an owner furnished transformer, Utility fed primary)?
