Researching a Generator Installation Project

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vilasman

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I have a project to install an emergency back up generator on a classroom, gym, library building of a school.
I am digging through the code book, the electricians handbook, the master I used to work for and friend of his to get inside on how to best put this together... but could it hurt to toss it out here and set some feedback?

The building has a 1200 amp main service. Currently the building has no emergency lighting. Not even battery packs. It does have a fire alarm and a sprinkler system. The sprinkler system as a 3 phase 480 volt pump. There is a 480v sump pump, sewage ejector pump, and a 480 volt pump to drain a nearby foot ball field. There is also a 240V ice melting system.

The one building is actually an older building and a newer addition, so there are 2 power rooms that are adjacent to each other. They share a wall.

There 5 power rooms in the building each contains 3 or 4 panels, none of which are more than half full. Usually one of the panels is 120/208 and another is 120/240. I believe, all of the outlying panels are fed from a 120/208, a 120/240, and a 277/ 480 panel in the new main power room or a similar set up in the old power room.

Now my plan, what my old master and I have come up with so far is this.

150Kva natural gas, generac 480/277v 225A out
225a fuse disconnect switch
300 Amp HTC series Generac transfer switch

225a fuse disconnect switch and then the utility feed going into the xfer switch

after transfer switch

trough
feed a 480V disconnect for the fire pump
feed a 480 volt mainbreaker panel for the other pumps.

feed a 75kva 477V to 240 volt transformer

From this point it get interesting. Plan A is to mount (2) 120/240v main breaker panels and a 20 amp disconnect. The disconnect feeds the fire alarm which is battery backed up. One of the 120/240v panels will feed the lighting circuits that I can corral from the 2 main power rooms and the ice melter.

What I haven't done is gone through each power room and figured out whether I can reconfigure the panels so that all the lighting circuits are in one panel in a given power room and then re-feed that panel from the main power room.


I took on this course of action because I felt it would be less work, than going through the whole building, re-wiring 3-4 lights in each room together and then running all that wire to one or more central locations. In other words, there are no always on lights in the building.

There is an theater in the building which has a battery powered back up lighting system.

Any thoughts?
 
First question to answer; Is this a back-up power installation or emergency power installation? One is for convenience and you can pretty much power what ever you want, the other has strict NEC requirements for life safety.

The first step, which is sounds like you've started is to define the use of the generator, and it sounds like emergency power is involved, so it sounds like a life safety install.

Then you need to do a good code review, which should include a little discussion with your AHJ to determine exactly what he is going to expect. A little up front due diligence goes a long way in avoiding rework after inspection.

You did not mention what size your fire pump is, and that will have a huge bearing on the generator size and capability.

Since it sounds like you have not done this before, I would recommend getting a PE on board to perform, as a minimum, a review of your proposed plan.
 
Some things to think about:
1. The "life safety" loads on the generator will need to have their own transfer switch.
2. The generator will need to be large enough to start the fire pump.
3. The transfer switch for the fire pump will need to be approved for use with the fire pump which usually means the fire pump will needs its own xfer switch.
4. Is the fire pump currently connected ahead of the main disconnect for the building?
5. Egress lighting, will this be on the generator?
 
well I talked to the chief electrical inspector about this today for the 2nd time.
I specfically asked about the separate transfer switch for the fire pump and he specifically said no I didn't need it.
He specifically said I did not need to do load calculations. He specifically said what I had to submit was a riser diagram. I also specifically said that the only lighting that I had to supply was the lighting in the hallways and the stairwells that is normally always on.

Fortunately I have a PE that I can reach out and touch so my planned/riser diagram will be reviewed by him.

The job is in your nation's capitol.

As for the fire pump. 480V 3 phase, fused at 30 amps.
 
vilasman said:
well I talked to the chief electrical inspector about this today for the 2nd time.
I specfically asked about the separate transfer switch for the fire pump and he specifically said no I didn't need it.
He specifically said I did not need to do load calculations. He specifically said what I had to submit was a riser diagram. I also specifically said that the only lighting that I had to supply was the lighting in the hallways and the stairwells that is normally always on.

Fortunately I have a PE that I can reach out and touch so my planned/riser diagram will be reviewed by him.

The job is in your nation's capitol.

As for the fire pump. 480V 3 phase, fused at 30 amps.
Click to expand...
Hopefully you got it in writing before his buzz wore off!:D
 
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