Service disconnect for generator

[Daja7]

I have recently run into a situation that is a new one for me. We installed a 20KW standby generator with a service entrance rated disconnect / transfer switch at the service. The generator is at the other end of the home. We ran the generator wiring in the crawl to the service disconnect. The inspector says that we need a service entrance rated disconnect at the generator as well.
No other county or locality has had this requirement. We have installed over one hundred of these in the last year with this being the only situation like this. He cites article 702.11. There is a disconnect via the generator breaker. and 702. says nothing about a service rated diasconnect.
Am i missing something?

 

[Gregg Harris]

I have recently run into a situation that is a new one for me. We installed a 20KW standby generator with a service entrance rated disconnect / transfer switch at the service. The generator is at the other end of the home. We ran the generator wiring in the crawl to the service disconnect. The inspector says that we need a service entrance rated disconnect at the generator as well.
No other county or locality has had this requirement. We have installed over one hundred of these in the last year with this being the only situation like this. He cites article 702.11. There is a disconnect via the generator breaker. and 702. says nothing about a service rated diasconnect.
Am i missing something?

702.12 Outdoor Generator Sets. Where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. The disconnecting means shall meet the requirements of 225.36.

This 2011 but if you generator has a UL 1008 listing you are done. 225.36 is your requirement for it to be service rated

 

[Daja7]

what does the ul 1008 listing do for this situation?

 

[Hendrix]

I have recently run into a situation that is a new one for me. We installed a 20KW standby generator with a service entrance rated disconnect / transfer switch at the service. The generator is at the other end of the home. We ran the generator wiring in the crawl to the service disconnect. The inspector says that we need a service entrance rated disconnect at the generator as well.
No other county or locality has had this requirement. We have installed over one hundred of these in the last year with this being the only situation like this. He cites article 702.11. There is a disconnect via the generator breaker. and 702. says nothing about a service rated diasconnect.
Am i missing something?

Think of it as a new service. You need a service rated disconnect as soon as the cable enters the building, or on the outside of the building. The generator enclosure is not concidered service rated.

 

[Gregg Harris]

what does the ul 1008 listing do for this situation?

It is the listing for a service rated disconect as required by 225.36

 

[Daja7]

702.12 Outdoor Generator Sets. Where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. The disconnecting means shall meet the requirements of 225.36.

This 2011 but if you generator has a UL 1008 listing you are done. 225.36 is your requirement for it to be service rated

I would agree that there be a disconnect but 702.12 does not state disconnect means shall meet 225.36 . aside, article 225 section II 225.36 deals with more than one building or other structure.
Does not seem to apply. Generator does not meet article 100 definition of a service. Conductors and equipment for delivering electrical energy from the "serving utility" to the wiring sytem of the premisis served. Seperately derive system is a Premis wiring system derived from a source other than a service. At least that is how i read it. i am just trying to get it straight as other localities agree with my assesment. We all could be wrong.

 

[Daja7]

Think of it as a new service. You need a service rated disconnect as soon as the cable enters the building, or on the outside of the building. The generator enclosure is not concidered service rated.

By definition a stand by sytem is not a service.Service is derived from the utility. it needs a disconnect for sure but it is a feeder. so service rated in my opinion does not apply. (could be wrong)

 

[augie47]

The problem I have had with 702.12 is that I have never seen any documentation to indicate the generator breaker "met the requirements of 225.36" ie: service rated.

 

[jap]

By definition a stand by sytem is not a service.Service is derived from the utility. it needs a disconnect for sure but it is a feeder. so service rated in my opinion does not apply. (could be wrong)

If you were to erase the last sentence of 702.12 which requires the disconnecting means to meet the
requirements of 225.36 then you'd be absolutely correct.

Question is, is the disconnecting means on the generator "Service Entrance Rated" or not.

If it is your good to go the way you installed it.
If not, the inspector is correct.

 

[jap]

If you win that argument,He could also bring up the argument of being "Within Sight" depending on where
the generator disconnect is located on your particular unit....... keep your fingers crossed.

 

[Daja7]

If you were to erase the last sentence of 702.12 which requires the disconnecting means to meet the
requirements of 225.36 then you'd be absolutely correct.

Question is, is the disconnecting means on the generator "Service Entrance Rated" or not.

If it is your good to go the way you installed it.
If not, the inspector is correct.

2011 code book 702.12 does not state "requirements of 225.36 must be met."

actually i just found a Mike Holt Neca explaination of generator installations on line and in it i clearly states that no additional disconnect is needed as long as the generator has a disconnecting means on it. Does not have to be service rated. I should have looked deeper to begin with.
Good discussion though. love Mike Holt

 

[augie47]

2011 code book 702.12 does not state "requirements of 225.36 must be met."

actually i just found a Mike Holt Neca explaination of generator installations on line and in it i clearly states that no additional disconnect is needed as long as the generator has a disconnecting means on it. Does not have to be service rated. I should have looked deeper to begin with.
Good discussion though. love Mike Holt

Huh ????? Are there 2 2011's ????? MIne says:

702.12 Outdoor Generator Sets. Where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. The disconnecting means shall meet the requirements of 225.36.

 

[kwired]

I would agree that there be a disconnect but 702.12 does not state disconnect means shall meet 225.36 . aside, article 225 section II 225.36 deals with more than one building or other structure.
Does not seem to apply. Generator does not meet article 100 definition of a service. Conductors and equipment for delivering electrical energy from the "serving utility" to the wiring sytem of the premisis served. Seperately derive system is a Premis wiring system derived from a source other than a service. At least that is how i read it. i am just trying to get it straight as other localities agree with my assesment. We all could be wrong.

Forget the generator for a moment and think about art 225. Art 225 is not dealing with services either, yet 225.36 still wants the disconnecting means to be of a type that is suitable for use as service equipment. Most fused disconnects or load centers are rated for use as service equipment, so you see very few cases of violations here. But a circuit breaker mounted inside a standby generator simply was not designed and/or tested for this purpose.

 

[mkgrady]

So when is a service rated disconnect not required between the generator and the ats?

 

[augie47]

So when is a service rated disconnect not required between the generator and the ats?

Possibly if the generator were within the premises. You would still need OCP for the conductors but Art 225 would not be involved.

 

[ceb58]

I would agree that there be a disconnect but 702.12 does not state disconnect means shall meet 225.36 . aside, article 225 section II 225.36 deals with more than one building or other structure.
Does not seem to apply. Generator does not meet article 100 definition of a service. Conductors and equipment for delivering electrical energy from the "serving utility" to the wiring sytem of the premisis served. Seperately derive system is a Premis wiring system derived from a source other than a service. At least that is how i read it. i am just trying to get it straight as other localities agree with my assesment. We all could be wrong.

The generator will meet the definition of "structure". So by that the wiring from the generator to the building are feeders that are covered under Article 225. By 702.12 the disconnect must meet 225.36. So reading 225.36 it takes you back to 225.31. Now when you put these two together you get a service rated disconnect for the conductors that supply or pass through the building or structure . Then looking at 225.32 it gives the location where this disconnect must be located .

 

[kwired]

Now mount generator so it is supported by the main structure, like on the roof, or on a wall bracket of some type, is it not part of the same structure now?

Put it on the ground a couple feet away (like is usually done) and it becomes more questionable as to whether or not it is a separate structure.

We do same thing with HVAC equipment but we always consider those to be part of the structure they serve. Otherwise the cheap AC disconnects commonly used are not rated for use as service equipment, and we should not be able to serve the "separate structure" with them.

 

[augie47]

Now mount generator so it is supported by the main structure, like on the roof, or on a wall bracket of some type, is it not part of the same structure now?

Put it on the ground a couple feet away (like is usually done) and it becomes more questionable as to whether or not it is a separate structure.

We do same thing with HVAC equipment but we always consider those to be part of the structure they serve. Otherwise the cheap AC disconnects commonly used are not rated for use as service equipment, and we should not be able to serve the "separate structure" with them.

makes perfect sense, does it not

 

[ceb58]

Now mount generator so it is supported by the main structure, like on the roof, or on a wall bracket of some type, is it not part of the same structure now?

Put it on the ground a couple feet away (like is usually done) and it becomes more questionable as to whether or not it is a separate structure.

We do same thing with HVAC equipment but we always consider those to be part of the structure they serve. Otherwise the cheap AC disconnects commonly used are not rated for use as service equipment, and we should not be able to serve the "separate structure" with them.

Comparing a generator to a HVAC unit is like............ comparing a generator to a HVAC unit. By definition a HVAC unit would be served by an individual branch circuit and its disconnecting means are covered under 440.11. Also by definition the wiring between a generator and the final BCOCD in the structure served would be a feeder that is covered by 225. Two different animals as far as the NEC is concerned.

 

[kwired]

Comparing a generator to a HVAC unit is like............ comparing a generator to a HVAC unit. By definition a HVAC unit would be served by an individual branch circuit and its disconnecting means are covered under 440.11. Also by definition the wiring between a generator and the final BCOCD in the structure served would be a feeder that is covered by 225. Two different animals as far as the NEC is concerned.

I wasn't comparing the generator to HVAC units, I was stating that in one situation we have a separate building or structure and rules in art 225 apply and yet in the other situation we still have just as much of a separate building or structure yet we say it is part of the main structure.

I don't care if the separate building or structure is a generator, an AC unit, a bulk tank or bin, or any other item directly associated with the main structure, the rules should be the same for all.