Fire Pump connection to generator

[steve66]

I am reviewing plans for an assisted living project. It has been suggested that if a generator is added to power emergency lights, then the generator would also have to be connected to the fire pump (and sized to run the fire pump).

From the NEC, it looks like it is up the the AHJ to determine if the utility is reliable enough to be a single supply. (In this case, I am acting as the AHJ). I can't find any other codes that say anything different.

I would welcome any opinions or code references.

Thanks:
Steve

 

[jtester]

Re: Fire Pump connection to generator

The NEC Handbook has a note indicating that NFPA 20 Standard for the Installation of Stationary Pumps for Fire Protection provides guidance for evaluating reliability. Have you looked there yet?
Jim T

 

[steve66]

Re: Fire Pump connection to generator

Jtester:

Yes, NFPA 20 gives the same wording as NEC does.

Thanks:
Steve

 

[hbendillo]

Re: Fire Pump connection to generator

I've run into this a lot. It is a judgement call that is difficult to make. In cases where the electrical supply is deemed sufficiently reliable we run a separate service directly to the fire pump from the secondary of the service transformer. In other cases the natural gas supply was deemed reliable enough to power small generators.

It also depends on the facility. We would never be allowed to do any of these for a Nursing Home, Prison, Hospital or similar facility. I think in those cases you better provide a feeder from he generator.

 

[sandsnow]

Re: Fire Pump connection to generator

steve
A fire pump by Art. 695 has to have a second source or a reliable source regardless of the e-lights being on a genset.

You as the AHJ have to make the call. Our utility guarrantees quality but not continuity of service. Based on that we do not accept a second service as being reliable.

 

[steve66]

Re: Fire Pump connection to generator

So it sounds like some would require an emergency generator for the fire pump, even if one wasn't going to provide one for the emergency lights?

To me, the catch 22 is this: I am permitted to decide that the utility is reliable enough. But then, if a generator is added for other reasons, that has no bearing on the reliability of the utility. Thus, I don't see how I can say they have to connect the generator to the fire pump.

Steve

 

[wirenut1980]

Re: Fire Pump connection to generator

I guess there is nothing that says that if the utility has a reliability score of X for their SAIFI, SAIDI, CAIDI, ASAI, or MAIFI then they are reliable enough...that you would be able to say ok the utility is reliable enough, or not. If it were me, I would put the fire pump on the generator because of the type of facility it is. I see your dilemma, though.

 

[steve66]

Re: Fire Pump connection to generator

I guess there is nothing that says that if the utility has a reliability score of X for their SAIFI, SAIDI, CAIDI, ASAI, or MAIFI

You lost me there. I don't know what any of those are. Sounds like you are thinking if the utility can provide a letter saying they are reliable (which is very unlikely), then great. Otherwise, a generator is needed.

Steve

 

[wirenut1980]

Re: Fire Pump connection to generator

Sorry, I'm pretty young and assume everyone else knows more than I do The acronyms I rattled off are reliability indices, or how utilities are graded. I'm not sure who they report these numbers to, maybe the Public utility commission?

Anyways, SAIFI stands for System Average Interruption Frequency Index and is calculated by dividing the total number of customer interruptions by the total number of customers.

SAIDI stands for System Average Interruption Duration Index and is calculated by dividing the customer interruption duration (in hours) by the total number of customers.

And the others are other variations of the same variables, and some have to do with demand and availability, and some break the interruptions down into momentary and extended durations.

Edit: Hey Charlie, is this really done by utilities? I learned about it in a Cooper Power continuing education course.

[ February 24, 2005, 05:13 PM: Message edited by: wirenut1980 ]

 

[cshaw]

Re: Fire Pump connection to generator

I have an alternate question on this topic. If the utility is accepted as being reliable and you wanted to go the extra mile and connect the fire pump to the generator, will the requirements of 695.4 still apply?

Alternately, if the utility service is not accepted as being reliable and generator connection is required, where in the generator distribution can I make my connection if I go by the statement in 695.3(B)(1) "A tap ahead of the on-site generator disconnecting means shall not be required." Does this give me relief from the requirements such as 695.4(B)(2)(3)"Not be located in equipment that feeds loads other than the fire pump" Example 1000kw gen with 1200A molded case breaker feeding a switchgear lineup thru a 1200A drawout breaker then have a 250A drawout breaker feed the controller/ats? Is the switchgear an acceptable place to make the generator connection based on 695.3(B)(1)?

 

[benaround]

Re: Fire Pump connection to generator

Steve,

80.21 (C)(3)

I don't think you have to figure this out for the summiter of the plans. They can do what they get paid to do and you can review it.

To be more clear,require a corrected plan to be submitted.

JMO

 

[volt101]

Re: Fire Pump connection to generator

Here is what I did:

Call the utility and ask them to give you in writing, a letter stating that their power is reliable. After they are done laughing at you, ask them for a circuit analysis on the system that feeds the area. The one that I needed it for showed that on an average of 2.3 times a year, the circuit losses power for over 120 minutes. Take that paper over to the fire department and ask them if they want to live with that kind of risk.

For my case:
1.) The fire pump waives the need for a second means of egress, even on the fourth floor.
2.) The hallways don't have windows.
3.) The emergency back up units in these halls are only required to last for 1 1/2 hours.
4.) After the 1 1/2 hours have elapsed, out come the candles.
5.) If a fire starts as a result of unattended candles, or even a cat knocks one over.
6.) Without power the fire pump does not start. Why was it that the second means of egress waived by the building codes? Oh yeah, it was because they had a fire pump.
7.) As people are trying to leave their only means of egress, that may I remind you, that they can be in complete darkness by now (1.5 hrs).

The city's fire department, even though I didn't want them to, they did....

Jim

 

[benaround]

Re: Fire Pump connection to generator

All they want to do is power some emg. lights ?

Instead of using a generator,the hot ticket now is UPS for emg. ,mostly rated with 3 hours backup 120vac or 277vac. So, would this still involve the fire pump?

Well, after what happened with 'Katrina' I think a nice big gen. set is a great idea!!!!

 

[sceepe]

Re: Fire Pump connection to generator

Steve,

This is an area that is intentionally vaugue because no one wants to be responsible for making the call. What is needed is a measurable reliability threshold below which the POCO supply is not judged reliable enough.

However, no one wants to be liable for setting the threshold. Not to mention, I'm sure the POCO lobby would fight it because they don't want any part of their grid judged as unreliable.

So in the absence of some objective measure of reliability, we are left with a hot potato that no one wants to hold. As an engineer, I am not going to make the decision as to much downtime is good enough to be reliable especially for a school or nursing home. As the AHJ you don't want to make that call either.

The result: If it has a fire pump, it gets a generator. Might be overkill, might be a waste of money. But from a liability standpoint its the safe way to go.

Now, If you size the generator for the fire pump, (which means it is way oversized to meet the voltage drop requirements), adding the emergency lights to it probably won't increase the size of the generator much. So you might as well put them on the gen set and avoid the maintenance hassle of all those battery packs.

 

[steve66]

Re: Fire Pump connection to generator

To let you all know what happened with this, the contractor called the State Fire Marshall and asked them. There response was that the utility was considered reliable, therefore, no generator was required.

I'm happy, because I didn't have to make the call one way or the other when the code left it vauge.

Steve

 

[bdarnell]

Re: Fire Pump connection to generator

Originally posted by steve66:
To let you all know what happened with this, the contractor called the State Fire Marshall and asked them. There response was that the utility was considered reliable, therefore, no generator was required.

I'm happy, because I didn't have to make the call one way or the other when the code left it vauge.

Steve

I ran up against this exact situation in a warehouse in New Jersey. My position was that I didn't have to put the fire pump on the genset and the AHJ asked me "If the utility supply is reliable, why are you installing a generator?" Good question..... We put the pump on the genset. And BTW the genset breaker has to be sized for locked rotor. I'm sure you already knew that.

 

[steve066]

Re: Fire Pump connection to generator

"If the utility supply is reliable, why are you installing a generator?"

That's a good point. The code does require a backup source for emergency egress lighting. Isn't that really saying the utility isn't reliable enough?

On the other hand, why didn't the code just require a backup source for a fire pump just like they did for emergency lighting? They must feel like some utilities are reliable enough.

That leaves me guessing that the CMP's somehow feel like emergency lighting is more important than a fire pump. Maybe because the likelyhood of an actual fire during a power outage is more remote.

Steve

 

[rick hart]

Re: Fire Pump connection to generator

That leaves me guessing that the CMP's somehow feel like emergency lighting is more important than a fire pump. Maybe because the likelyhood of an actual fire during a power outage is more remote.

I think what they are getting at is fire pumps control property damage while the lights and such can get people out for either fire or anty other type of emergency.
Sizing a generator for a firepump is not really cost effective since the firepump load is rarely present when doing testing of the generator. That leads to having to add artificial loads to bring the generator up to operating load.