Fire pump Installation Questions

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faresos

Senior Member
Hello Everyone:

I’m working on a project where a fire pump upgrade is required. The current fire pump will be replaced with like capacity. However, after further investigation I found the following:

1. This is a high rise building where the building house a MV 13.8KV utility switchgear. The building is served from three-MV 13.8KV feeders from different substation (2-preferd & Reserve).
2. There are multiple double ended unit substations serving the building. The unit substations steps down the 13.8KV to 480V.
3. The existing fire pump is currently fed from a switchboard that is fed from the unit substation via 800A fuse. No other source is feeding the pump. The feeder to the pump is served from overhead conduits.

My conclusions are:

1. The fire pump doesn’t comply with the NEC code requirement due to the fire pump needs to be powered from two different sources; one normal source and a generator or two normal sources (since the two service feeders are coming from two different substation). Is this correct?
2. Does the feeder to the fire pump coming from the switchboard as described above a code compliance or it has to come directly from the unit substation?
3. The current fire pump is 75HP but the fuse size used in the switchboard to feed 800A, I believe it should 600% of the motor FLA, correct?
4. The current feeders to the fire pump are ran overheads with conduits and wires, I believe this needs to be fire resistant assembly such as MI cable, correct?
5. I’m thinking to bring this to code by powering the new pump with two feeders from two alternate normal sources but will be from switchboards down stream of the unit substations since no spare fuses are available in unit substation (The use of generator as an alternate feed is a challenging due to the condition of the generators), change the feeders to MI cables if no other options are available. Do you see any issue with this approach?
6. Someone mention that I have to keep 10ft separation between the two fire pump feeders, not sure where this come, any idea?

Thanks,
 
The ten foot separation is reasonable to reduce the odds of one mechanical event to the building taking out both feeders, but I also am not sure what code it might be in.
 
faresos said:
Hello Everyone:

I’m working on a project where a fire pump upgrade is required. The current fire pump will be replaced with like capacity. However, after further investigation I found the following:

1. This is a high rise building where the building house a MV 13.8KV utility switchgear. The building is served from three-MV 13.8KV feeders from different substation (2-preferd & Reserve).
2. There are multiple double ended unit substations serving the building. The unit substations steps down the 13.8KV to 480V.
3. The existing fire pump is currently fed from a switchboard that is fed from the unit substation via 800A fuse. No other source is feeding the pump. The feeder to the pump is served from overhead conduits.

My conclusions are:

1. The fire pump doesn’t comply with the NEC code requirement due to the fire pump needs to be powered from two different sources; one normal source and a generator or two normal sources (since the two service feeders are coming from two different substation). Is this correct?
2. Does the feeder to the fire pump coming from the switchboard as described above a code compliance or it has to come directly from the unit substation?
3. The current fire pump is 75HP but the fuse size used in the switchboard to feed 800A, I believe it should 600% of the motor FLA, correct?
4. The current feeders to the fire pump are ran overheads with conduits and wires, I believe this needs to be fire resistant assembly such as MI cable, correct?
5. I’m thinking to bring this to code by powering the new pump with two feeders from two alternate normal sources but will be from switchboards down stream of the unit substations since no spare fuses are available in unit substation (The use of generator as an alternate feed is a challenging due to the condition of the generators), change the feeders to MI cables if no other options are available. Do you see any issue with this approach?
6. Someone mention that I have to keep 10ft separation between the two fire pump feeders, not sure where this come, any idea?

Thanks,
Click to expand...

I'd take item 3 and item 6:

3. The FLA of a 75HP pump is 83 amps. The locked rotor current referred to Table 430.251(B) is 543 amps. That means you can't assume 600% for all types of motor.

6. What GoldDigger said. Refer to 225.34(B) for the provision requiring services to be "sufficiently remote from each other".
 
faresos said:
Hello Everyone:

I’m working on a project where a fire pump upgrade is required. The current fire pump will be replaced with like capacity. However, after further investigation I found the following:

1. This is a high rise building where the building house a MV 13.8KV utility switchgear. The building is served from three-MV 13.8KV feeders from different substation (2-preferd & Reserve).
2. There are multiple double ended unit substations serving the building. The unit substations steps down the 13.8KV to 480V.
3. The existing fire pump is currently fed from a switchboard that is fed from the unit substation via 800A fuse. No other source is feeding the pump. The feeder to the pump is served from overhead conduits.

My conclusions are:

1. The fire pump doesn’t comply with the NEC code requirement due to the fire pump needs to be powered from two different sources; one normal source and a generator or two normal sources (since the two service feeders are coming from two different substation). Is this correct?
2. Does the feeder to the fire pump coming from the switchboard as described above a code compliance or it has to come directly from the unit substation?
3. The current fire pump is 75HP but the fuse size used in the switchboard to feed 800A, I believe it should 600% of the motor FLA, correct?
4. The current feeders to the fire pump are ran overheads with conduits and wires, I believe this needs to be fire resistant assembly such as MI cable, correct?
5. I’m thinking to bring this to code by powering the new pump with two feeders from two alternate normal sources but will be from switchboards down stream of the unit substations since no spare fuses are available in unit substation (The use of generator as an alternate feed is a challenging due to the condition of the generators), change the feeders to MI cables if no other options are available. Do you see any issue with this approach?
6. Someone mention that I have to keep 10ft separation between the two fire pump feeders, not sure where this come, any idea?

Thanks,
Click to expand...

1. Fire pumps can be supplied by one source where the source is reliable. See 695.3(A). Check with your AHJ to see what they deem to be reliable. NFPA 20 also gives some direction.

2. Feeders from a distribution point are only allowed to supply fire pumps at multi building campus style complexes. See 695.3(C)

3. The overcurrent protection has to be sized to carry the locked rotor current indefinitely. The locked rotor current is not necessarily 600% of running current.

4. Service conductors that supply fire pumps have to be installed outside of the building or installed in accordance with 230.6(1) or (2) per 695.6(A)(1). Feeder conductors inside of a building have to be installed using one of the methods listed in 695.9(A)(2)(d)(1) through (3).

5. A single source is acceptable if reliable. I feasible, I would just propose a new service just for the fire pump.

6. I have never heard of a 10 ft. separation requirement.
 
topgone said:
I'd take item 3 and item 6:

3. The FLA of a 75HP pump is 83 amps. The locked rotor current referred to Table 430.251(B) is 543 amps. That means you can't assume 600% for all types of motor.

6. What GoldDigger said. Refer to 225.34(B) for the provision requiring services to be "sufficiently remote from each other".
Click to expand...

Thanks all for the replies!

So lets say will need to size the overcurrent protection device based on the locked rotor current which is 543A, do we need to do MINIMUM of 125% of the 543A so it will not trip if it was running more than 3hrs?

Thanks,
 
packersparky said:
1. Fire pumps can be supplied by one source where the source is reliable. See 695.3(A). Check with your AHJ to see what they deem to be reliable. NFPA 20 also gives some direction.

2. Feeders from a distribution point are only allowed to supply fire pumps at multi building campus style complexes. See 695.3(C)

3. The overcurrent protection has to be sized to carry the locked rotor current indefinitely. The locked rotor current is not necessarily 600% of running current.

4. Service conductors that supply fire pumps have to be installed outside of the building or installed in accordance with 230.6(1) or (2) per 695.6(A)(1). Feeder conductors inside of a building have to be installed using one of the methods listed in 695.9(A)(2)(d)(1) through (3).

5. A single source is acceptable if reliable. I feasible, I would just propose a new service just for the fire pump.

6. I have never heard of a 10 ft. separation requirement.
Click to expand...

As far item 2, wouldn't the existing fire pump conductor considered a branch circuit and not a feeder since it's powered from a down stream switchboard from a unit substation? I'm thinking now to reuse this existing feeder and bring a backup feeder form a standby generator (I just found out that a back up feeder from generator is required per GSA standard).

also, would a Federal high rise building (30 floors) considered to be Multibuilding campus style complex or it needs to be multiple separate buildings?
 
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