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.
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.