Multiple source fire pump feeder and OCPD requirments

[nzubrzycki]

1) I'm working on a building where the fire pump ats/controller is multiple-fed by a normal source (secondary tap of service transformer) and a stand-by generator source. Per NEC 695.6 (A) exception, am I required to concrete encase or 2-hour protect ONLY the conductors on the load side of the ATS? Or am I supposed to protect the normal and emergency feeds as well? The way I read the exception, it seems to me that if using multiple sources to feed the fire pump, then only the conductors on the load side of the transfer switch have to be protected by means of concrete encasement or 2-hr fire rated wiring.

2) Is MI cable considered a 2-hour rated assembly?

3) Am I required to provide a supervised disconnect or is this optional per 695.4 (B) (i.e. "shall be permitted" to me sounds like it's optional).

Thanks

 

[cleveland]

Hmmmm......... fire pumps! 8-( It reads like you don't have to have the 2 hour rating but if the normal feed is a tap from the utility transformer it sure looks to me like we'll have service entrance conductors coming through a building with no OC protection. Seems like that single disconnecting means with overcurrent protection on the normal feed upstream would be of great value. If you don't have it and someone needs to work on the fire pump ATS you'd have to shut down the building transformer wouldn't you? We ended up adding just such a switch to allow for servicing the ATS.

MI cable should meet the need for the 2 hour rating but note that the code wants a listed assembly, etc.

 

[augie47]

As far as question 1 is concerned, I think you have to look at from two standpoints, Art 695 and Art 230.
You are correct, that with multiple sources, as far as Art 695 is concerned, you would not need the fire separation, but 230.6 stands alone as far as service conductors, so, unless you have a service switch ahead of the ATS, you would need to address 230.6

(2) I don't see any exceptions for MI cable

(3) As I read the provisions of 695.4(B), the disconnect "shall be permitted", but if used, the supervising in (5) is mandatory.

Note: I have encountered instances where the local Fire Marshall would not allow such a disconnect regardless of NEC.

 

[nzubrzycki]

Thank you both for the answers. Very helpful.

 

[Strife]

1: No, both feeders have to be basically (outside of the building. Check code on definitions being outside of building)
2: Cables don't give a fire rating. The encasement around them (drywall, concrete, buried, etc) does.
3: I don't think so, generally you want everything to melt before the fire pump gives up. After all if you have a fire, protecting the pump that helps putting the fire out doesn't help much. Does it?

1) I'm working on a building where the fire pump ats/controller is multiple-fed by a normal source (secondary tap of service transformer) and a stand-by generator source. Per NEC 695.6 (A) exception, am I required to concrete encase or 2-hour protect ONLY the conductors on the load side of the ATS? Or am I supposed to protect the normal and emergency feeds as well? The way I read the exception, it seems to me that if using multiple sources to feed the fire pump, then only the conductors on the load side of the transfer switch have to be protected by means of concrete encasement or 2-hr fire rated wiring.

2) Is MI cable considered a 2-hour rated assembly?

3) Am I required to provide a supervised disconnect or is this optional per 695.4 (B) (i.e. "shall be permitted" to me sounds like it's optional).

Thanks