Generator NEMA 3R ATS and service disconnect

[DonP520]

I hope someone can help answer a Service Disconnect question. I have a police station with a 500 kw 277/480 3 Phase standby generator and Nema 3R ASCO ATS. The generator has a CB installed from the factory, the output conductors from the generator terminate on the emergency lug in the ATS. The intire building is on standby generator. The secondary side of the Utility transformer terminates in the ATS on the normal lugs, and then the load terminates in a switch gear main CB. The first OCPD is in the electrical room in the switch gear. Is there a requirement to have a service disconnect/ OCPD before the utility terminates at the ATS? Would the ATS fall under ART 230.82 and be consitered a tap on the supply side of the service disconnect?

Thanks for your help

 

[augie47]

A service disconnect is needed. 230.82 is your correct reference, A non-service rated ATS is not one of the items allowed to be ahead of your service disconnecting means.

 

[DonP520]

Thanks for your reply. I was on the right track but was given some wrong information. The Normal side is feed from the switch gear and not the Utility Transformer Secondary. Thanks.

 

[templdl]

Thanks for your reply. I was on the right track but was given some wrong information. The Normal side is feed from the switch gear and not the Utility Transformer Secondary. Thanks.

Very basically to have an ATS as service disconnect you would have to have an enclosed OCPD to terminate you service on which is SE rated. I'm not sure if ASCO offers an SE rated device by itself without adding a breaker.
I know that Eaton Electrical (Cutler Hammer) has a breaker typt transfer switch that does offer a SE rated device. Commonly their ATS consists of(2) molded case switches but they are also available manufactured with breakers that are TM. Adding the requirements to be SE allows the to offer an SE rated ATS.