Disconnecting means ahead of ATS

[Red Wiggler]

I have a situation where we are installing a genset to serve an exisiting building. Our plan is to interupt the service conduits running into the building and route this normal power into a Pad Mounted Service Rated NEMA 3R Automatin Transfer Switch located next to the proposed Genset.

My question is... Do I need a disconnect means to be installed ahead of the transfer switch now because it is ahead of my Service equipment (Main Panelboard) that is located in the building?

The neutral that is derived from Genset, and the neutral coming from the 4-wire service will meet in the ATS. Do I tie these neutrals together, or do I need a need a 4 Pole ATS that isolates the individual neutrals?

 

[augie47]

If you ATS is service rated and your service conductors are outside of the building up to your pad ATS you should not need a service disconnect ahead of the ATS, however, you might run it by POCO as sometimes they have special requirements.

Switching the neutral vs solid neutral is an engineering determination, but if you TS is not designed for neutral switching, then, yes you do connect the neutrals together.

 

[chris kennedy]

Our plan is to interupt the service conduits running into the building and route this normal power into a Pad Mounted Service Rated NEMA 3R Automatin Transfer Switch located next to the proposed Genset.

I agree with Gus, but don't forget to rework the main bonding jumper as per 250.28.

 

[don_resqcapt19]

If the transfer switch becomes the service disconnect and if it does not have the service OCPD in it, you will have to install the service OCPD immediately adjacent thereto. 230.91