Fire Pump Feed From Meter Stack

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LibertyEngineering

Senior Member
Location
Allentown, PA
I have an interesting (or maybe common and not so interesting) scenario I could use some opinions on

Fire pump feed from a utility meter stack. Power company wants fire pump feeder metered (of course) this is a small stack only 3 meters no main on the stack. 2 meters for tenants one for a fire pump. The 2 meters for the tenants will have a 200A breaker in the stack. The meter for the fire pump is interesting. First – we decided feeding the fire pump out of the stack is acceptable because there is no main in the stack and the feed comes from its own compartment within the stack keeping the feed separate from other sections. If we do not have a breaker in the stack for the fire pump doesn’t the feed for the fire pump become a feeder tap from the stack? The feed is less than 25’ so 25’ tap rule applies however;
The ampacity of the tap conductors must not be less than one-third the rating of the overcurrent device that protects the feeder.
There is no OCP protecting the feeder being tapped. This feeder would be the service conductors from the utility company’s transformer which feeds the stack.
The tap conductors terminate in a single circuit breaker, or set of fuses rated no more than the tap conductor ampacity in accordance with 310.15 [Table 310.15(B)(16)].
There is OCP in the fire pump controller so should be able to comply with this one by matching the feeder ampacity to the OCP.

Since the whole point of a fire pump feeder is to have nothing in its circuit which can interrupt the flow of electricity to it. Is it an issue to feed the fire pump from the stack without OCP even though it technically is a feeder tap from the stack which has no OCP. If the stack did have a main than we would need to tap ahead of the main anyway. In a nutshell any fire pump feed is going to be a tap which would not comply with the tap rule since it needs to be ahead of and not within the same enclosure as the main.
One really needs to think about this before responding as I have changed my mind several times as to what I would allow.
 

packersparky

Senior Member
Location
Wisconsin
Occupation
Inspector
I have an interesting (or maybe common and not so interesting) scenario I could use some opinions on

Fire pump feed from a utility meter stack. Power company wants fire pump feeder metered (of course) this is a small stack only 3 meters no main on the stack. 2 meters for tenants one for a fire pump. The 2 meters for the tenants will have a 200A breaker in the stack. The meter for the fire pump is interesting. First – we decided feeding the fire pump out of the stack is acceptable because there is no main in the stack and the feed comes from its own compartment within the stack keeping the feed separate from other sections. If we do not have a breaker in the stack for the fire pump doesn’t the feed for the fire pump become a feeder tap from the stack? The feed is less than 25’ so 25’ tap rule applies however;
The ampacity of the tap conductors must not be less than one-third the rating of the overcurrent device that protects the feeder.
There is no OCP protecting the feeder being tapped. This feeder would be the service conductors from the utility company’s transformer which feeds the stack.
The tap conductors terminate in a single circuit breaker, or set of fuses rated no more than the tap conductor ampacity in accordance with 310.15 [Table 310.15(B)(16)].
There is OCP in the fire pump controller so should be able to comply with this one by matching the feeder ampacity to the OCP.

Since the whole point of a fire pump feeder is to have nothing in its circuit which can interrupt the flow of electricity to it. Is it an issue to feed the fire pump from the stack without OCP even though it technically is a feeder tap from the stack which has no OCP. If the stack did have a main than we would need to tap ahead of the main anyway. In a nutshell any fire pump feed is going to be a tap which would not comply with the tap rule since it needs to be ahead of and not within the same enclosure as the main.
One really needs to think about this before responding as I have changed my mind several times as to what I would allow.

The conductors are not feeder taps. A feeder has overcurrent protection. They are service entrance conductors, and from your description, it seems to be in compliance with 695.3(A)(1).
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
If you pull the meter, will the pump run? If the answer is "no", that's the first thing you need to fix. The tap really needs to be made ahead of the stack. 310.15 isn't going to apply. If you have a disconnect or OCPD, it has to be rated for the locked rotor current of the pump (see NFPA 20). The conductors only need to be sized to 125% of the FLA.
 

LibertyEngineering

Senior Member
Location
Allentown, PA
If you pull the meter, will the pump run? If the answer is "no", that's the first thing you need to fix. The tap really needs to be made ahead of the stack. 310.15 isn't going to apply. If you have a disconnect or OCPD, it has to be rated for the locked rotor current of the pump (see NFPA 20). The conductors only need to be sized to 125% of the FLA.

I'l have to check with your question regarding pulling the meter as that is a good point. As far a tapping ahead of the stack the power company will not allow it. The fire pump service must be metered , for obvious reasons. If pulling the meter kills the feed than I will have to convince the power company I need a CT service not a self contained service. They use self contained for class 320 & 480 meter base services which is 400A & 600A, 120/208V 3 Phase. Pulling the meter on a CT service will not kill the service to the pump. I do know about the locked rotor current requirement.

Thanks
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I'l have to check with your question regarding pulling the meter as that is a good point. As far a tapping ahead of the stack the power company will not allow it. The fire pump service must be metered , for obvious reasons. If pulling the meter kills the feed than I will have to convince the power company I need a CT service not a self contained service. They use self contained for class 320 & 480 meter base services which is 400A & 600A, 120/208V 3 Phase. Pulling the meter on a CT service will not kill the service to the pump. I do know about the locked rotor current requirement.

Thanks

I totally don't get that. It's a separate service, basically, and it only runs 1) during testing or 2) if the building is on fire. Do they really care about the 1/2 hour or so per year it operates? And if the building goes empty and they pull the meters, the fire pump MUST run.
 

packersparky

Senior Member
Location
Wisconsin
Occupation
Inspector
I totally don't get that. It's a separate service, basically, and it only runs 1) during testing or 2) if the building is on fire. Do they really care about the 1/2 hour or so per year it operates? And if the building goes empty and they pull the meters, the fire pump MUST run.

Every fire pump service that I have ever seen has had a meter. The presence of a meter is not a code violation. The utility could just as easily disconnect it at the transformer or street.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Every fire pump service that I have ever seen has had a meter. The presence of a meter is not a code violation. The utility could just as easily disconnect it at the transformer or street.

Interesting. Every fire pump installation I've been involved with has the service tap ahead of the CT cabinet.

While it's true that the POCO could disconnect the service at the transformer or street, isn't it more usual that they pull the meter?
 
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