Emergency/Back up power switch gear

[WiscElectrician]

Hello all,

I have a question regarding feeding a new construction building out of our existing HQ gear.

Currently the generator switch gear is fed from a 2500A generator located in the CUP. The feeders come in to the switch gear and into a center mounted 2500A main breaker. This then feeds an attached switch location adjacent to the left and right with a shared bus. To the left is the 700 series emergency lighting and to the right feeds the elevators and data center switch gear.

We are looking at feeding the new conference center out of our standard building feed to a new ATS which is also fed from the generator switch gear described above. We are being told by the gear guys that we cannot feed the new conference center ATS out of the right side of the generator gear where we have the space because the conference center backup will contain the emergency lighting?

So the question is - Why would it matter from a design standpoint if we fed the conference center out of the right side of the generator switch gear? My thoughts are it is already set up for emergency back up duty and shares a bus with the other two non emergency breakers anyway?

Thank you for any replies. I just want to be prepared when we sit down for a meeting with the gear guys, inspector and our design engineers.

 

[jumper]

What does CUP mean?

 

[GoldDigger]

If the panel bus really is electrically continuous to both sides with no intervening OCPD or disconnect, then there is no practical reason to make the distinction.
But I suspect that somebody is considering the two half sections of bus to be feeders and each one therefore cannot be shared. However, the same argument can be applied to a setup with the main at one end of a bus.
An argument can be made that there needs to be a separate breaker for the two different category loads before the multiple feeder breakers. The design goal is to keep the two load groups separated as far upstream as possible. In which case you would probably need two feeds to the new building in any case!

 

[steve66]

I don't see a problem feeding the conference center out of the right side, as long as you provide emergency power for the emergency loads.

That could be a separate feeder out of the left side of the switchgear to an emergency ATS, or it could be battery powered emergency and exit lights.

Since you have the huge generator, I'm assuming you want to avoid the battery packs.

So you just need to figure out if the left side has enough capacity to power the new emergency loads. That's usually a relatively small load.

 

[roger]

What does CUP mean?

Actually I think he may be referring to a Central Utility Plant

Roger

 

[jumper]

Actually I think he may be referring to a Central Utility Plant

Roger

Thank you.

 

[WiscElectrician]

Yes, sorry for the late response. The CUP as I stated above refers to the utility plant where we house the generator, drycoolers, cooling towers and pumps. Thank you for the replies.