Generator and Multiple Service Disconnects

[bcorps]

I have a project where the main utility is coming into the building, and hitting a gutter on the inside of the exterior wall, from which 4 panels beneath it (all with main breakers) are fed. Nothing too exotic there. However, they want the entire building backed up by generator. My instinct is is that I can just intercept the feeder, and put a service-rated transfer switch ahead of the gutter. Does this transfer switch then effectively become the single service disconnect, allowing me to add as many panels as I need downstream, tapping the gutter feeder? (None of the existing panels is labeled as Service # of # currently, though if they would remain so, I will call for them to be labeled as such).

 

[charlie b]

Does this transfer switch then effectively become the single service disconnect. . . ?

Yes. It also becomes the location of the main bonding jumper (i.e., the N-G bond), so that you need to run EGCs from that point to the gutter. Also, the wires running to the gutter are no longer "services," but rather are "feeders."

Welcome to the forum.

 

[bcorps]

Yes. It also becomes the location of the main bonding jumper (i.e., the N-G bond), so that you need to run EGCs from that point to the gutter. Also, the wires running to the gutter are no longer "services," but rather are "feeders."

Welcome to the forum.

Thanks for reminding about the service bond. Great catch. I will then need to unbond the neutrals and grounds in the existing panels (if they were even done like that to begin with).

I was a member here for many years, but my posts got "lost" at some point when the forum was changed. But thanks for the welcome anyway!

 

[LarryFine]

All of which means all of the neutrals must be isolated from the EGCs in the four panels, and any bonding screws/jumpers removed.

Everything past the new disconnect will become sub-panels. Don't forget to relocate the DECs if necessary, too.


Hmmm. Will the incoming service conductors be allowed to share the same gutter as the tapped feeder conductors?

 

[david]

IHowever, they want the entire building backed up by generator.

How are they currently dealing with egress lighting?

Does this transfer switch then effectively become the single service disconnect, allowing me to add as many panels as I need downstream, tapping the gutter feeder?.

The original service conductors where not subject to feeder "tap" rules, remember the equipment grounds will be sized to the main service disconnect from the new service disconnect to the now existing (feeder) panels

(None of the existing panels is labeled as Service # of # currently, though if they would remain so, I will call for them to be labeled as such).

From the information you posted this building only originally had one service and from what you posted when your done the building will still only have one service

This buildings life safety, is most likely unit equipment but that needs clarified, if not you may need a separate transfer switch and an NE panel