Generator Wiring

[jkflipflop67]

Designing a 480V emergency generator backup for a local municipality and there is no room to physically put the generator near the incoming line service or automatic transfer switch. In fact, the generator has to be located outside the far side of the building. Do the conductors from the generator to the automatic transfer switch have to be treated as Service Entrance conductors and be run around the outside of the building (or underground)?

 

[rcwilson]

Re: Generator Wiring

IMO - Specify the generator with an integral circuit breaker mounted on the generator, now the conductors are protected and can be run as you see fit.

240.21 (G) (2002 NEC) allows using the inherent overload protection of the generator to protect the cables. Since the conductors would be protected, I don't see the need to treat them similar to Service Entrance Conductors. A breaker would still be required at the transfer switch to protect the switch and load conductors.

I am assuming that this is an optional standby system so Article 700 does not apply.

Keeping the generator conductors separated from other wiring and protected from physical damage by running underground might provide additional security for the standby system.

I can't find any requirement to treat generator cables as service conductors. The generator does not meet the definition of a service.

(I'm very interested in what others think about this.)