Adding generator for electric fire pump

[tom baker]

For an existing fire fire pump station, have a 100 HP electric and a 1500 gpm diesel fire pump. There are frequent power outages, causing the diesel fire pump (DFP) to run, the DFP has proved unreliable (broken shaft, overheated injectors). Proposal is to install a diesel generator so the DFP would not run in a outage.
Art 695 calls this a "on site standby generator"
Article 700 in Emergency Systems has an note that gives examples of emergency systems, which includes fire pumps.

So what type of generator will this be, Emergency, Legally Required Standby, Optional Standby?
It makes a huge difference on the installation requirements.
And would all the power wiring in the fire pump station, now powered from POCO, be required to be identified per 700.10 (A)?
Also the new requirement for an alternate source of power in 700.3(F) is challenging, look at this if you haven't in the 2017 NEC

 

[charlie b]

My answer is that this would be an optional standby load.

First of all, what does this building do for a living? I mean does the electric fire pump run all the time, providing pressure to fire hydrants in the surrounding community? Just trying to understand the situation.

Secondly, the informational note to which you refer gives fire pumps as an example of what could be classified as an emergency load. That does not put you into the ballpark by itself. The real answer lies in the 700.2 definition of “emergency systems.” Did the city of Bremerton (I presume that is the jurisdiction of concern here) declare that the electrical fire pump is an emergency load? If not, did they declare it a legally required standby load? If not, you are in article 702.

I believe that my interpretation is consistent with 695.3(B)(2), which allows the utility source to be backed up by a generator. I believe it is also consistent with 695.3(D), which does not say anything that would lead the reader to believe that article 700 comes into the picture.

By the way, given the likely cost of the proposed generator and transfer switch, has the city considered simply replacing the diesel fire pump with one that is more reliable?

 

[gadfly56]

My answer is that this would be an optional standby load.

First of all, what does this building do for a living? I mean does the electric fire pump run all the time, providing pressure to fire hydrants in the surrounding community? Just trying to understand the situation.

Secondly, the informational note to which you refer gives fire pumps as an example of what could be classified as an emergency load. That does not put you into the ballpark by itself. The real answer lies in the 700.2 definition of “emergency systems.” Did the city of Bremerton (I presume that is the jurisdiction of concern here) declare that the electrical fire pump is an emergency load? If not, did they declare it a legally required standby load? If not, you are in article 702.

I believe that my interpretation is consistent with 695.3(B)(2), which allows the utility source to be backed up by a generator. I believe it is also consistent with 695.3(D), which does not say anything that would lead the reader to believe that article 700 comes into the picture.

By the way, given the likely cost of the proposed generator and transfer switch, has the city considered simply replacing the diesel fire pump with one that is more reliable?

All other things being equal, this is likely the most cost effective solution, unless the 100 HP pump is, in fact, running all the time. On the other hand, I think that unlikely. Fire pumps are not designed as continuous duty equipment, and a 100 HP pump is not going to provide a lot of "oomph" for district-wide fire mains. As you indicate, more info is needed.