Question
I have a residential customer that I completely wired his new house . I installed a 400 amp service with two 200 amp panels. The meter base has two 200 amp breakers. One breaker feeds one of the 200 amp panels. The other 200 amp breaker feeds the normal side of a automatic transfer switch. A 40 kw generator with a main breaker in the generator feeds the generator side of the transfer switch. The load side of the transfer switch feeds the second 200 amp panel. This generator is not a seperately derived system as neutral at generator is not bonded to generator frame and neutrals are bonded together in transfer switch. Neutral is not switched. My question is as follows. It is possible that the utility power could be present feeding the one panel that is not on the generator at the same time the generator could be running feeding the generator panel. This could happen if the 200 amp breaker feeding the normal side of the transfer switch tripped or was turned off. Since the neutrals are tied together in the transfer switch and both power sources are on would one system try to feed back on to the other system by way of the neutrals. I know that by theory they are trying to return to the power source. I have not ran generator yet but am planning on this next week. Utility company gave me the o.k. but this is a very expensive home I do not want to take a chance on damaging anything or burn the house down. I have talked to several people including a Electrical Engineer. They said it seems o.k. with them. But if something happens it will be on me.
Please reply only if you have experience with this set up. Please no theory.
Thank You,
I have a residential customer that I completely wired his new house . I installed a 400 amp service with two 200 amp panels. The meter base has two 200 amp breakers. One breaker feeds one of the 200 amp panels. The other 200 amp breaker feeds the normal side of a automatic transfer switch. A 40 kw generator with a main breaker in the generator feeds the generator side of the transfer switch. The load side of the transfer switch feeds the second 200 amp panel. This generator is not a seperately derived system as neutral at generator is not bonded to generator frame and neutrals are bonded together in transfer switch. Neutral is not switched. My question is as follows. It is possible that the utility power could be present feeding the one panel that is not on the generator at the same time the generator could be running feeding the generator panel. This could happen if the 200 amp breaker feeding the normal side of the transfer switch tripped or was turned off. Since the neutrals are tied together in the transfer switch and both power sources are on would one system try to feed back on to the other system by way of the neutrals. I know that by theory they are trying to return to the power source. I have not ran generator yet but am planning on this next week. Utility company gave me the o.k. but this is a very expensive home I do not want to take a chance on damaging anything or burn the house down. I have talked to several people including a Electrical Engineer. They said it seems o.k. with them. But if something happens it will be on me.
Please reply only if you have experience with this set up. Please no theory.
Thank You,
