Generator Disconnect

[curt swartz]

I have designed a generator installation for a single family dwelling. I plan to install a meter-main which will feed the utility side of an automatic transfer switch. I plan to install a circuit breaker as a service disconnect between the supply conductors of the generator and the generator side of the transfer switch. There is also a circuit breaker located in the generator installed by the manufacture. The generator is going to be located at least 100? from the equipment locations. All of this equipment is located outside The AHJ has issued comments on this design and says that I can not use the circuit breaker at the house as a disconnecting means. He says since the generator is located more than 50? from the transfer switch I must provide a listed lockable disconnect at the generator.

I don?t under why I need an additional disconnect. What purpose is there in adding an additional lockable disconnect at the generator? The service disconnect on the house will completely disconnect the generator from the house so the only portion of the circuit that will still be energized are the underground conductors from the generator. The factory installed circuit breaker in the generator will provide overload and short circuit protection. I don?t see how this installation is any different than installing a meter main on the pole then feeding a main breaker panel at the house.

Any comments would be appreciated.

 

[steve66]

Re: Generator Disconnect

The only thing I see wrong is that someone working at the transfer switch couldn't lock out the generator. (I'm assuming the breaker at the disconnect isn't lockable). But I'm not sure if that is a code violation. It seems like one could also lock out the fuel supply or the starting circuit if they were worried about the generator starting.

Steve

 

[dillon3c]

Re: Generator Disconnect

100 foot away ..I'm just wondering,is the "factory-installed disconnecting means"- internal to housing and generator driving means..Might it under a lock and cover?-Just wondering mind you...

 

[physis]

Re: Generator Disconnect

I'm reading 445.18 and it doesn't mention within site from anything. It looks to me like at least that section is satisfied.

 

[dillon3c]

Re: Generator Disconnect

702.11 Outdoor generator sets.
Where an outdoor housed generator set is equipped with a readily accesible disconnecting means located within sight of building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure.

Article 100
Accessible Readily-(Readily Accessible)

Capable of being reached quickly for operation,renewal,or inspections without requiring those to whom ready access is requisite to climb over or remove obstacles or resort to portible ladders,and so forth.

*Like I was saying.. 100 foot.. I'm really not sure..I have installed separate disconnecting means for generator sets, where internal means was not readily accessible and or under,locked cover..Like I said,just shooting and do not know conditions of generator set..

*just fishing..could be wrong..

[ July 01, 2005, 11:57 AM: Message edited by: dillon3c ]

 

[physis]

Re: Generator Disconnect

Well how can that be? If generators could be used for emergency or optional standby power then article 700 701 and 702 would have been mentioned in the index under generators.

Of course I'm kidding. But I'm not kidding that those articles are left out of the index.

You must be using 2005 Dillon cause I don't have a 702.11 or any mention of disconnect in 702 in the 2002. And we're on 1999 still in California.

 

[curt swartz]

Re: Generator Disconnect

Thanks for the comments.

The reason I?m installing the service disconnect at the house adjacent to the transfer switch is that the generator is not within site. I don?t see why the disconnect for the generator circuit needs to be at the generator.

I was planning to use a single 3R circuit breaker enclosure with a 2-pole 200 amp breaker. This would be installed where the generator conductors emerge from the ground and within 12? of the transfer switch.

 

[dillon3c]

Re: Generator Disconnect

Sam..
I'm sorry bud.Yeh I'm quoting the '05 and I did forget Cal.is cycles behind sir..Forgive me for not adding statement of '05..

dillon-

[ July 01, 2005, 11:55 AM: Message edited by: dillon3c ]

 

[physis]

Re: Generator Disconnect

I think your inspector's confusing requirements.

Edit: No need to be sorry Dillon, it gave me a reason to read up on the 700's.

[ July 01, 2005, 11:58 AM: Message edited by: physis ]

 

[benaround]

Re: Generator Disconnect

Curt,

445.18 never mentions the (noun) disconnect.

As far as 2002NEC I see your installation as code compliant, except for any local requirments,Also many times a simple EMO is used for emergency shut down of generator.I feel the Inspector is in error.

frank

 

[dillon3c]

Re: Generator Disconnect

benaround,sam,
Returning and reading into this more,and inlight of what steps curt has taken in installation Inspector could be confused.

I'll be interested in judgement call..

 

[curt swartz]

Re: Generator Disconnect

I called the building official today regarding this issue. He said that the reason he wanted a lockable disconnect at the generator is because there would still be energized conductors at the house if the house disconnect is open. I asked him how this was any different than the utility feed since those conductors are still energized with the service disconnect off. He has now decided that my proposal is fine as long as the generator provides includes overcurrent protection which it does.

This is actually the first time I have had any contact with the building department regarding this project. I provided all the information to the GC who is working with the home owner to obtain the permit. The generator is only a small portion of the building project.

Thanks for the comments and have a great 4th.

 

[physis]

Re: Generator Disconnect

I didn't see that he gave you a code reference.

You have a good fourth too Curt.

 

[LarryFine]

Re: Generator Disconnect

Curt, keep in mind that, unless the generator is a 50KW unit, its disconnect doesn't need to be rated for 200 amps, or greater than the internal breaker (115% aside).

I used a typical (lockable) 60a. AC pull-out disconnect for a recent generator install. The generator has an internal 60-amp breaker, but I used #2 (because of the run) AL SER.

The point is that the wiring between each source (utility or generator) and the transfer switch need only be capapble of carrying the available current of that source.