Fire Pump Back-Up

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artcatal

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I plan to have installed a new electric fire pump motor on existing water service entering a building. The utility company (JCP&L) provides commercial power to the building and would also connect to the fire pump via an ATS. I want to back-up the fire pump with an emergency generator. Currently, there is an existing working natural gas emergency generator in the building. Could I use this existing natural gas generator (or even a new one) for back-up or is there a code requirement that says a diesel fueled generator must be used?

Kindly let me know.

Art
 
I want to back-up the fire pump with an emergency generator.
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Are you calling it that? Do you really want to call it that?

The requirements of Article 695 are independent of those in Article 700 unless otherwise mandated by the authority having jurisdiction. If 700 applies then does 700.12 General Requirements (B) Generator Set (3) Dual Supplies Prime movers shall not be solely dependent on a public utility gas system for their fuel supply or municipal water supply for their cooling systems. Means shall be provided for automatically transferring from one fuel supply to another where dual fuel supplies are used.
Exception: Where acceptable to the authority having jurisdiction, the use of other than on-site fuels shall be permitted where there is a low probability of a simultaneous failure of both the off-site fuel delivery system and power from the outside electrical utility company.

Code doesn't care if it is diesel or nat or lp, garbage, waste oil, etc.... just that it will get fuel and run!

Jim
New Hampshire
 
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Art

I'd encourage you to carefully evaluate why the utility feed isn't considered reliable. I've done numerous fire pumps that didn't require on-site generation. Some will some won't, and there isn't enough info in your post to make that judgement.

Jim T
 
artcatal said:
I plan to have installed a new electric fire pump motor on existing water service entering a building. The utility company (JCP&L) provides commercial power to the building and would also connect to the fire pump via an ATS. I want to back-up the fire pump with an emergency generator. Currently, there is an existing working natural gas emergency generator in the building. Could I use this existing natural gas generator (or even a new one) for back-up or is there a code requirement that says a diesel fueled generator must be used?

Kindly let me know.

Art
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If you are backing up a fire pump, then your generator is an emergency generator and is governed by the requirements of articles 695 and 700.

There is almost no chance that the existing generator will meet the requirements of NFPA 13 / 20 and article 695. Most notibly 695.7 which requires no more than 15% voltage drop when starting the fire pump. Unless a generator is specifically sized for a fire pump (which means oversizing the alternator) it will probably not be able to achieve this voltage drop limitation.

Like someone else said, you may be able to argue that the utility power supply is "reliable". See 695.3B. In which case a backup generator is not needed. In my experience, the AHJ will not define reliable because they want you to assume the liability for that decision. So get a list of outages over the last two years and see what the downtime % is. Then make the call is 99.9% reliable? How about 99.8%?
 
sceepe said:
Like someone else said, you may be able to argue that the utility power supply is "reliable". See 695.3B. In which case a backup generator is not needed. In my experience, the AHJ will not define reliable because they want you to assume the liability for that decision. So get a list of outages over the last two years and see what the downtime % is. Then make the call is 99.9% reliable? How about 99.8%?
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99.9% reliable is not very reliable in electric service terms. If a service is 99.9% reliable it has averaged 8.65 hours of outage a year. I'm not sure anyone would be comfortable with that duration of outage(s).

I remember, while working for an electric utility, our CEO told the whole community that our system was 99% reliable. That translated to 3.65 days of outage each year, a totally unacceptable number for a customer in a large city.

Reliability is measured in many ways, only one of which is "total amount of time that service is available". Often only one measure of reliability is inadequate.

Jim T
 
jtester said:
99.9% reliable is not very reliable in electric service terms. If a service is 99.9% reliable it has averaged 8.65 hours of outage a year. I'm not sure anyone would be comfortable with that duration of outage(s).
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Which is why a lot of designers put in a generator when they see a fire pump. The code won't define it, the AHJ won't define it. So the designer assumes the liablility for the POCO's ability to provide power. Perhaps you could present the reliabilty measurement (however you want to measure it) to the owner and let them tell you (in writting) if that is reliable enough. Otherwise I'd give them a new generator.
 
I always understood that only the AHJ could rule on whether the service was reeliable enough or not. The commentary in the Handbook says that, and if I remember correctly so does NFPA 20, although I don't have a copy of it nearby.

I doubt that if you ask, they will OK a single feed as being reliable. When I worked for a utility, we once installed primary lines from two separate substations to a hospital to provide reliable service according to the AHJ.

Jim T
 
In High Rise buildings our Building Code (currently 1997 UBC) requires a genset for the Fire Pump when a Fire Pump is required.

With the above requirement, the reliability factor is a non-issue.

I can only think of one low rise bldg in my area where a fire pump was required. Turned out to be a diesel prime mover anyway.Other areas may see different scenarios.

Our POCO will not give us any official reliability stats or percentages. They guarantee quality but nothing on interruption. That being said, they take great pride in their system and in making sure downtime is kept to a minimum.
 
jtester said:
I always understood that only the AHJ could rule on whether the service was reeliable enough or not. The commentary in the Handbook says that, and if I remember correctly so does NFPA 20, although I don't have a copy of it nearby.

I doubt that if you ask, they will OK a single feed as being reliable. When I worked for a utility, we once installed primary lines from two separate substations to a hospital to provide reliable service according to the AHJ.

Jim T
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Even if the AHJ doesn't require a generator, it might still be possible for the engineer to be held liable.

And just how is an AHJ going to decide if a utility is "reliable". Even if the AHJ decides the utility is reliable today, who is to say the POCO won't let their system go to pot 10 years down the road? This is one area where I think NFPA copped out. They should have provided some type of guidelines.

And the UBC requirement only applies to high rises. What about all the smaller buildings?
 
steve66 said:
And the UBC requirement only applies to high rises. What about all the smaller buildings?
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Not meaning to be smart aleck, but what about them?

In my city, in additon to the reason you gave, there is also the issue of small utilities being created inside larger utilities. Such as a City owned utility. So we would require a genset.

The hi-rise rule just makes that discussion easier.
 
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