Another ATS question

[buddhakii]

I have a 600 amp service feeding a main breaker as the service disconnect. From there it goes into a an ATS that is also fed from a generator. This is an SDS as there is no neutral from the generator. My question is does the ATS or the disconnect on the Generator need to be suitable for use as Service Equipment?

 

[DARUSA]

I have a 600 amp service feeding a main breaker as the service disconnect. From there it goes into a an ATS that is also fed from a generator. This is an SDS as there is no neutral from the generator. My question is does the ATS or the disconnect on the Generator need to be suitable for use as Service Equipment?

Do the TS switch the neutral ? Why is not neutral from the generator?

 

[augie47]

If you have overcuurent protection in the service ahead of the ATS then the ATS does not have to be service rated.

 

[buddhakii]

That's what I thought augie. Inspector says either the ATS has to be service rated or the generator has to have a service rated breaker. To aswer your question darusa, there is no need for a neutral from the generator in this application.

 

[volt101]

Educated Guess Here - Inspector must be quoting 225.36. He/She will probably allow a added disconnect that is SUSE rated placed inside or outside near the point of entry to the building.

 

[augie47]

Educated Guess Here - Inspector must be quoting 225.36. He/She will probably allow a added disconnect that is SUSE rated placed inside or outside near the point of entry to the building.

I see his point and I agree. Take a look at 702.11 [or 701.11(B)(5)]
which will reference you back to 225.36.
Someone with more experience with service rated transfer switches will have to help here because I don't see how that is acceptable as the ones I have seen only have OCP on the "service" side.
It would seem to me the generator breaker or an added service rated OCP would be needed but that's not what the Code states.

 

[volt101]

It would seem to me the generator breaker or an added service rated OCP would be needed but that's not what the Code states.

It is what the code is saying. It would seem to me that the generator manufacturers should actually read the code and get their disconnects a "Suitable for Use as Service Equipment" sticker.

 

[augie47]

Just a thought: so many of the units I've seem don't meet another part of the requirement : "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."
Often the disconnecting means is not readily accessible, thus an additional disconnect means is needed at the building anyway.

 

[buddhakii]

So what I read is that the generator disconnecting means has to meet requirement of 225.36, but does the ATS also have to be suitable for use as service equipment? Inspector told me either the ATS has to be suitable for use or the breaker in the generator. Either one would satisfy as far as he is concerned. As far as I can tell the Generator neccesarily has to be service rated but the transfer switch just has to be suitable for it's intended use per 702.6.

 

[ceb58]

So what I read is that the generator disconnecting means has to meet requirement of 225.36, but does the ATS also have to be suitable for use as service equipment? Inspector told me either the ATS has to be suitable for use or the breaker in the generator. Either one would satisfy as far as he is concerned. As far as I can tell the Generator neccesarily has to be service rated but the transfer switch just has to be suitable for it's intended use per 702.6.

You can have two set ups. A service rated ATS will have ocp/disco built into the ATS for the main service and gen. Or you can have a ATS that is not service rated which would require separate ocp/disco installed for the main and gen.
As said the breaker on the gen.set probably will not meet 225.36 or 445.18. You will need to install a disco for the gen. set.