Service Entrance Rated ATS Confusion

[xguard]

Am I wrong that for an Automatic Transfer Switch to be Service Entrance Rated it is to have an OCPD located in it and some means of manual disconnect?

Please correct my below conductor classifications as needed:

Service Entrance Conductors - From the Meter to the ATS
Feeder - From the Load Side of the Service Entrance Rated ATS to the Indoor Panel with MCB.
Feeder - From the Generator Circuit Breaker to the ATS.

Assuming the above is correct then is it fair to say that conductors between the ATS and panel being supplied in a building can not be considered underground service conductors (assuming they are underground) and thus have an ampacity of only 100% of the load NEC 230.31 (A)?

 

[iwire]

Am I wrong that for an Automatic Transfer Switch to be Service Entrance Rated it is to have an OCPD located in it and some means of manual disconnect?

The manual disconnect for sure. However the OCPD can be located immediately adjacent to it.

Please correct my below conductor classifications as needed:

Service Entrance Conductors - From the Meter to the ATS
Feeder - From the Load Side of the Service Entrance Rated ATS to the Indoor Panel with MCB.
Feeder - From the Generator Circuit Breaker to the ATS.

I agree

is it fair to say that conductors between the ATS and panel being supplied in a building can not be considered underground service conductors (assuming they are underground)

They are feeders, nothing in 230 applies to them.

 

[xguard]

The manual disconnect for sure. However the OCPD can be located immediately adjacent to it.




I agree




They are feeders, nothing in 230 applies to them.

Where is the requirment or the allowance for the OCPD to be adjacent to it? Not challenging it just can't find it. Thanks.

 

[augie47]

230.91
I've never seen a "service rated" ATS that not have INTEGRAL overcurrent protection, but my world is small

 

[iwire]

230.91
I've never seen a "service rated" ATS that not have INTEGRAL overcurrent protection, but my world is small

I don't have much experience with service rated transfer switches but if I recall the UL General directory does not mention OCP as a requirement for the listing.

 

[GoldDigger]

See [2011] 208

230.208 Protection Requirements. A short-circuit protective device shall be provided on the load side of, or as an integral part of, the service disconnect,

No mention of distance, but on the load side of can be interpreted as located before any other devices or loads at least. I suspect that an unfused disconnect followed by six or fewer breakers would not be seen as the service disconnect. The breakers would collectively assume that function.
A special case is the disconnect some POCOs require on the line side of their meter. It is pretty clear that this is NOT the service disconnect.

 

[iwire]

230.208 is in VIII. Services Exceeding 600 Volts, Nominal.

Just saying ...

 

[Smart $]

See [2011] 208


No mention of distance, but on the load side of can be interpreted as located before any other devices or loads at least.

[2011] 230.208 is for over 600V.

600V and less falls under...

230.91 Location. The service overcurrent device shall be
an integral part of the service disconnecting means or shall
be located immediately adjacent thereto.

While not explicit, I assume "immediately adjacent thereto" means no equipment other than conductors can be between the disconnect and OCPD electrically, and distance must be minimal for whatever method is used. JMO, but a transfer switch between disconnect and OCD would be non-compliant.

I suspect that an unfused disconnect followed by six or fewer breakers would not be seen as the service disconnect. The breakers would collectively assume that function.

If it's not seen as the service disconnect, the disconnect could be considered non-compliant. Certainly debatable, as the requirement does not say you cannot use a breaker, or more than one for that matter. Also consider a disconnect followed by more than one set of fuses. Not specifically prohibited to my knowledge.

 

[PetrosA]

For a manual Service Rated transfer switch containing no OCD or fuses, both Ronk and Eaton make them. It took some discussion with the inspector and theory talk about how "adjacent to" could mean the main breaker of a 200A loadcenter on the load side of the switch, but I've gotten my permits for them. In one case the MTS was indoors, next to two MB panels while in the most recent situation I will be mounting the switch outside between the meter and main panel in the basement.

 

[xguard]

For a manual Service Rated transfer switch containing no OCD or fuses, both Ronk and Eaton make them. It took some discussion with the inspector and theory talk about how "adjacent to" could mean the main breaker of a 200A loadcenter on the load side of the switch, but I've gotten my permits for them. In one case the MTS was indoors, next to two MB panels while in the most recent situation I will be mounting the switch outside between the meter and main panel in the basement.

How would you size the conductors between the MTS (Outdoors) and Panel (Indoors)? They don't seem to be service entrance conductors or feeders necessarily.