Fire Pump Feeder or Service Conductor

[Simon2015]

Hello,

Can you please tell me if the Tap rule: "The ampacity of the Tap conductor is not less than one third of the rating of the overcurrent device protecting the feeder conductors" [240.21(B)(2) and (4)] applies to the conductors feeding the overcurrent device? Please see the single line below for reference. My confusion is if those conductors are considered "Service conductors" or "Feeder conductors", I have understood that, that tap rule doesn't applies to Service conductors. Where in the NEC or NFPA can I find something in specific to this matter?.


Thank you.

 

[augie47]

You pretty much quoted your own proof in 240.4. The Tap conductor definition refers to overcurrent devices ahead of the tap. You have none if those are service conductors.


If the diagram happens to show non-service (SDS), then the 240.21(C) transformer secondary rules would apply.

 

[texie]

As augie said, these are not "taps" bur rather service conductors so tap rules don't apply.
As a point of observation, why are you using a service disconnect? Most designers would omit this as full service fire pump controllers are service rated. It saves a lot of cost and is one less point of failure.

 

[Simon2015]

- Thank you Augie47.

- Texie, the reason why I'm using an Overcurrent protection is because the Fire Pump is located approx. 500 Ft away from the substation and also because these conductors are going to be installed inside of the building in EMT, not encased in concrete but using wires listed fire-resistive [695.6(2)(2)], so I thought that is a good reason to add an extra protection.

Any opinions or comments are welcome.

Thanks.