Additional Disconnect means if generator is over 50 ft b

[cvanhouten]

I have a situation were our Standby Generator is located 53 feet from the building. We are using a 3-pole transfer switch and have a solid neutral through the transfer switch. Thus, we do not have a separately derived system correct. In the code book it say if the generator is within sight of the building than you do not need an additional disconnect means at the building. The definition of within sight say no more than 50 ft away. It also say if the conductors are not grounded. Wouldn't these conductors be grounded so we would not have to provide the extra disconnect? This is not a required emergency back by code, the owner has elected to provide a generator to backup the whole building (telephone co.) So the main service is 600A at 120/208V 3-phase. The transfer switch is in the building and service rated with the utility main breaker in the panel, the generator has a main breaker outside in the generator enclosure. Let me know if this is not enough information.

Thanks

[ February 09, 2005, 04:20 PM: Message edited by: cvanhouten ]

 

[tom baker]

Re: Additional Disconnect means if generator is over 50 ft b

If the generator is not required by NEC, then its an optionally required standby generator per Art 702. A disconnect is not required per the 2002 NEC, but that requirement has been added for the 2005. Do you understand why the disconnect is required and that is has no relationship to the conductors being grounded.
What do you mean the conductors are grounded? Are you referring to the grounded neutral conductor?

 

[cvanhouten]

Re: Additional Disconnect means if generator is over 50 ft b

thanks Tom,

No, sorry to say I do not know why it is required. Is it because they figure that is the most someone can see something accurately. As for the grounding I am referring to the way the they word it in section 702.11 "an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure." Why does it say ungrounded conductors vs just conductors if it does not matter.

 

[charlie b]

Re: Additional Disconnect means if generator is over 50 ft b

Originally posted by cvanhouten: Why does it say ungrounded conductors vs just conductors if it does not matter.

Because you never have to have a disconnect for the grounded conductor.

But your installation does not appear to meet this section anyway. If your generator?s disconnect is really 53 feet from the building, and if it cannot be moved closer (or an addition made to the building to make it closer), then you will need another disconnect at the building.

 

[tom baker]

Re: Additional Disconnect means if generator is over 50 ft b

OK now I see it. Often on a generator we need to know whats going on with the grounded neutral conductor, to know if neutral to case bond is required in the generator.