Multiple Switchboards, One Fire Pump

[necnotevenclose]

Let's say you have multiple swithboards in a high rise and one of those switchboards feed another switchboard which is fed via an emergency generator which connects to a fire pump. For clarity the fire pump is served from (2) sources of power normal & generator.

Question:
In order for the fire pump to provide complete building protection do the other switchboards need to tie into the emergency swbd?

 

[sceepe]

Let's say you have multiple swithboards in a high rise and one of those switchboards feed another switchboard which is fed via an emergency generator which connects to a fire pump. For clarity the fire pump is served from (2) sources of power normal & generator.

Question:
In order for the fire pump to provide complete building protection do the other switchboards need to tie into the emergency swbd?

I am notevenclose to understanding what you are talking about. I'm glad you added the "for clarity" part but I'm afraid its not enough.

In answer to you question, the arrangement of the distribution system (switchboards and emergency swbd) is irrelevant to a properly installed fire pump system. The fire pump has to be fed from a separate emergency system transfer switch that is rated for fire pump use. The only other loads that can be fed from that transfer switch are "emergency loads" such as emergency lights. Good luck trying to find a transfer switch rated for fire pump use. You can not install a panel downstream of the transfer switch and feed the generator and other emerency load from it. Anyway, many (most) fire pump controllers have an integral transfer switch.

The source of normal power CAN NOT come from one of your switchboards. It must be directly from the POCO xmfr (or tap ahead of the main). So it doesn't matter how you connect switchboards, the fire pump is fed either directly from the utility xfmr or from a tap befroe the first switchboard.

Also, are you sure all of these are switchboards? A panelboard is not the same as a switchboard which is not the same as switchgear. But thats a topic for another post.

 

[sandsnow]

Make sure it is really a "Fire Pump". People mistake booster pumps and pressure maintenance pumps for true "fire pumps"

 

[necnotevenclose]

By code if you are not in an area with reliable power than don't you need to utilize multiple sources? Also isn't it then up to your local AHJ to determine how the fire pump is connected? And if you have multiple switchboards and you tap off of one of the switchboards with main lugs only as one of the means to serve the fire pump and then the generator as the other source then shouldn't that comply to the NEC based on multiple sources?

My question was not meant to confuse but to ask if you have (3) switchboards (all seperatly served from utility but share common ground) and one of those switchboards served the generator and also had another normal feed coming out of that same switcboard to feed the fire pump through an ATS would that switchboard have to see a fault before the generator and fire pump would be activated on? Or are there seperate controls that would sense a failure in the system and turn on the generator to initiate the fire pump?

 

[sceepe]

By code if you are not in an area with reliable power than don't you need to utilize multiple sources?

This is true. If so, why are you asking about a generator? Also, have you ever found an AHJ that would define reliable? I have not. They always want to leave that definition and the associated liability to the engineer.

And if you have multiple switchboards and you tap off of one of the switchboards with main lugs only as one of the means to serve the fire pump and then the generator as the other source then shouldn't that comply to the NEC based on multiple sources?

I thought you said the power was "reliable"? How do you have a switchboard that is fed from the utility company. (i.e. a service entrance) that is main lugs only. I think your gonna need a main breaker or disconnect. You can feed the fire pump from a point ahead of this main breaker or disconnect (line side) but not from the the load side.

My question was not meant to confuse but to ask if you have (3) switchboards (all seperatly served from utility but share common ground) and one of those switchboards served the generator and also had another normal feed coming out of that same switcboard to feed the fire pump through an ATS would that switchboard have to see a fault before the generator and fire pump would be activated on? Or are there seperate controls that would sense a failure in the system and turn on the generator to initiate the fire pump?

The generator does not initiate the fire pump. The fire pump comes on if the pressure in the sprinkler system drops (because it is spraying water). What do you mean when you say "one of those switchboards served the generator". Do you mean that it supplies an ATS that was also supplied by the generator? If so, don't worry about this ATS, your gonna need another one dedicated to the fire pump.

What you want is a fire pump controller with integral transfer switch. Supply this with two feeds. One feed comes from a generator. The other feed comes from the utility company. This utility company feed can originate somewhere between the POCO xmfr secondary and the line side of the service disconnect. If you do this, you do not have to worry about faults in the system. If the main breaker in any of your switchboards were to trip, the fire pump does not see it. It is connected upstream of the switchboards. The fire pump controller will start the generator when it sees a loss of utility power. It does not care what is happening in your switchboards.

 

[bdarnell]

And if you have multiple switchboards and you tap off of one of the switchboards with main lugs only as one of the means to serve the fire pump and then the generator as the other source then shouldn't that comply to the NEC based on multiple sources?

Your fire pump tap must located ahead of and not within the same enclosure as your service disconnecting means.

 

[necnotevenclose]

Your fire pump tap must located ahead of and not within the same enclosure as your service disconnecting means.

bdarnell thank you for your reply. So if I'm understanding your comment correctly in order to provide multiple sources of power in an area that is not considered reliable I would need to provide an additional tap from the utility transformer to serve the fire pump and another feed to the fire pump via the generator. Is that correct? If I'm correct than this is very expensive since a service entrance rated disconnect and additional meter would need to be provided in order to prevent any back feed to the utility transformer. So that leaves me curious how is the utility tap configuration any different than providing a OCPD in MLO switchboard which serves the fire pump? In both cases you are protecting the equipment servicing the fire pump. But coming from the MLO switchboard would be a lot more cost effective.

Again thank you for the comment. To all please keep the comments coming in.

 

[bdarnell]

...since a service entrance rated disconnect and additional meter would need to be provided in order to prevent any back feed to the utility transformer.

How would a backfeed occur ? You will have to have a fire pump rated transfer switch as was mentioned earlier in the thread if I'm not mistaken, so that takes care of any backfeed problem.

Fire pump controllers are SE rated and your conductors must remain outside of the building as defined in Art. 695, so I'm not sure why you would need a SE rated disconnect. Your fire pump service disconnect is in the controller. As far as the metering goes, I'm not sure how you are metered, so you might need another utility transformer, CT cabinet, or whatever.

If I might suggest, you need to thoroughly read and understand Art. 695 and also NFPA 20. Fire pump installations are not hard to understand once you know what the intention of the standards are, but there isn't any latitude in the way you install them. It has to be done as specified in the codes.

Oh, and NFPA 20 is available directly from NFPA as a downloadable PDF file (for a nominal fee )

 

[mshields]

Let me get this straight

Let me get this straight

You've got a main switchboard feeding another switchboard which feeds a generator which feeds a Fire Pump.

You can't have the generator feeding into the same system as the utility source unless you have paralleling switchgear!

Maybe I misunderstood your description!

 

[ramdiesel3500]

necnotevenclose
Here where I work, we have done many many fire pump services. So far, we have always done them the same way. First, we arrange with the utility company to meter incomming power right at the tranformer pad utilizing CTs in the secondary side of the transformer cabinet. This way, the building service and firepump service will be on the same meter. We run a separate service raceway from this utility transfomer directly to the fire pump controller. The controller comes from the fire pump manufacturer as a part of their equipment package and has the tranfer switch included internally. It is SE rated! Next we install a raceway from the generator directly to the fire pump controller. These raceways must stay "outside of the building" until they are within 10 feet (local AHJ here) of the building (buried raceways are considered outside even when under the building slab). Since power from the generator originates from a circuit breaker, the breaker must have an overcurrent setting that is higher than the locked rotor current of the pump motor. Our main generator supplier puts a "fire pump rated" breaker in the generator cabinet (probably less $$ than a large breaker).
I hope this helps. This is basically the very same thing Sceepe and Brad just told you, but I thought you might like to hear how we do these in Indiana.