Fire Pump on Generator

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tkb

tkb

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Location
MA
I looked at a job the other day that was a new 100 kw generator, ATS and new 480v 3p panelboard for the generator loads.

They want to connect computer and HVAC loads to this generator.

I thought that it all was good until they said that they wanted the Fire Pump on the generator also.

Without the fire pump I would call this a Standby System and not a Legally Required Standby System.

This job is in MA where we amend the 05 NEC.
700.9(D)(1) would require a two hour fire rated room and wiring.

The existing fire pump is connected to the line side of the main in the switchgear. The fire pump feeder leaves the top of the switchgear and goes to the fire pump disconnect in the same room as the switchgear. The load from the disconnect leaves the disconnect then is run through the wall to the outside and runs along the building to the fire pump at the other end of the building.

They want to connect the fire pump to the generator load panel.

I think that they need to add a second main breaker to the generator or connect the fire pump to the line side of the generator main and a second transfer switch listed for fire pumps and rated for the locked rotor current of the fire pump. And the normal source needs to remain.

Does the fire pump disconnect and transfer switch need to be in a two hour rated room and wiring outside the room be 2 hr rated also?

I am going to talk to the local AHJ, but what do you think?
 
Re: Fire Pump on Generator

I'm not in MA, but I tend to agree this generator and installation needs to meet all the rules for running a fire pump.

If they installed a 100KW generator, and did not provide backup power to the generator, I would also have a problem with that.

Steve
 
Re: Fire Pump on Generator

We recently installed a generator in a building that had an existing fire pump. There are a lot of issues that come up when designing an installation like this.

First, I would try to meet with the AHJ and get his/her take on Art. 695 and NFPA 20. There are some ambiguities and sentences open to interpretation and arguement in both stndards.

You are correct that the fire pump will need it's own transfer switch which will have to be rated for fire pump service and it has to be interfaced with the existing fire pump controller, so it would be in your best interest to see if you can get the same brand transfer switch as the controller. That will make your job a lot easier. Study the diagrams published in NFPA 20 and decide how best to work the transfer switch into your existing scheme.

You do not have to connect the fire pump feeder ahead of the generator main, but the generator must be capable of starting and running the fire pump (not locked rotor).

Good luck.
 
Re: Fire Pump on Generator

It can be very expensive.
The transfer switch can not be in the same room as the fire pump.
Art 695 was only added to the NEC in 96, many of the rules are in NFPA20. Find out from your AHJ what version of NFPA 20 they are on, and get a copy.
 
Re: Fire Pump on Generator

Can the fire pump transfer switch be locatated outside?
 
Re: Fire Pump on Generator

Originally posted by tom baker:
The transfer switch can not be in the same room as the fire pump.
Click to expand...
Tom -

NFPA 20 9.6.4 states " Transfer of power to the fire pump controller between the normal supply and one alternate supply shall take place WITHIN the pump room".

Am I misreading this ?
 
Re: Fire Pump on Generator

Generator guy here. I've done many genset projects 100kW+ with fire pump applications.

You need to feed the fire pump off a 2nd main breaker mounted on the genset. Check local code but ideally we would recommend using a mag only breaker. You never want that breaker to trip on overload if the building is burning down. Let the wires melt! If you don't go mag only then you can go 250% on a thermal-mag.

If the genset is already built/shipped or installed then you can run into problems trying to retrofit another main. If the genset is UL2200 listed and you want to keep that listing then you have to follow the 125% overload rule. That means that the sum of all the generator mounted main breakers must be rated between 100% and 125% of the rated generator output. So in your case, 100kW, 480V...that genset is rated at 150A. The breaker ratings, when added together, must be between 150A and 187.5A.

Another thing you may or may not be thinking of is starting kVA on the fire pump. How is it being started? Across the line or soft start / VFD? If it's across the line then you may not have enough starting kVA available at the genset. Take your fire pump HP times 6 for a ballpark. That number is your required skVA. Ask the genset manufacturer the rated alternator skVA at 15% instantaneous voltage dip. When starting you don't want your voltage to dip anymore than that for a fire pump. The last thing you want is for the motor to drop out during a fire.

Just sitting here, I can come up with a LOT more questions. Email me at mikepgh@gmail.com if you need more help. The BEST thing to do is to call your local genset guy...whatever make you have...and get them involved.
 
Re: Fire Pump on Generator

Bdarnell:
I was going from memory I had just attended a great class on fire pumps by UL
 
Re: Fire Pump on Generator

Good luck finding a transfer switch listed for fire pump service. I've tried and had a lot of trouble. There is a special U.L. category and only a few manufactures listed. Much easier to find a combination controller and transfer sw.
 
Re: Fire Pump on Generator

Originally posted by sceepe:
There is a special U.L. category and only a few manufactures listed. Much easier to find a combination controller and transfer sw.
Click to expand...
True statements. And a lot easier to install.
 
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