Fire Pump

[cestone]

I have been an electrical designer for 20 years. I am using the 2008 NEC for my design. I thought I had a firm grasp of the fire pump code, but when my project manager contacted a previous designer for his opinion, I can no longer rely on my interpretation of the code based upon what he was told by the previous employee. I have been reading all sorts of forums on Fire Pump electrical installations lately trying to make some sense of what I am being told.

I have been designing the normal/emergency service feed to the fire pump from an ATS underground to the Fire Pump Control panel. The ATS also serves other emergency loads by a distribution panel to emergency branch panels. I have a stand-by Generator feeding the emergency side of the ATS.

I am being told that the NEC requires a breaker between the power source and the fire pump control panel and that breaker should only be for short-circuit protection. I have information from Sq D that states if the Fire Pump is fed by a service, the circuit breaker is sized to carry the LRA indefinitely. Where a generator serves the fire pump, the NEC allows me to use Table 430.52 instead of setting the breaker at LRA. Table 430.52 sizes the breaker at a max. of 250% of the motor. In my design, I have both.

The fire pump is a 20HP 208volt 3 phase motor. It has always been my understanding that the NEC prefers no breaker between the source (utility or stand-by generator) and the fire pump control panel.

Can someone shed some light on this situation for me?

Thank you so much for your help

 

[dkidd]

There are two good articles on EC&M


http://www.ecmweb.com/mag/electric_abcs_fire_pump/index.html

http://www.ecmweb.com/nec/electric_power_pump/index.html

The NEAMA publication ICS 14 is also a good refernece

An electronic copy may be downloaded at no charge, or a hard copy purchased for $60.00 by visiting NEMA’s Web site at www.nema.org/stds/ics14.cfm

There are also two white papers at

http://www.schneider-electric.us/si...echnical-library/applications/fire-pumps.page

 

[david luchini]

I don't believe that the NEC requires a breaker between the power source and the fire pump controller, however, it permits one. See 695.4(A) and (B).

Your ATS sounds like a violation of the NEC to me, however. The power source must connect to a "listed fire pump power transfer switch" or "listed combination fire pump controller and power transfer switch." I don't think sharing the fire pump and other emergency loads is permitted on the ATS.

 

[steve66]

I don't believe that the NEC requires a breaker between the power source and the fire pump controller, however, it permits one. See 695.4(A) and (B).

Your ATS sounds like a violation of the NEC to me, however. The power source must connect to a "listed fire pump power transfer switch" or "listed combination fire pump controller and power transfer switch." I don't think sharing the fire pump and other emergency loads is permitted on the ATS.

I also think it is a violation: The more common way to supply a fire pump with a generator is to have a single fire pump controller with a built in ATS.

Also, I believe that the smaller breaker size is only allowed between the generator and ATS. Any disconnect that the utility supply runs through would have to be sized for the locked rotor current.