Powering new Fire Pump

[Reesh14]

I am working on a design for a new pump room addition to an existing building. The pump room shall have a fire pump (7.5HP,208V,3ph), jockey pump (1.5HP,208V,3ph), and other equipment (unit heater, lighting, fan, and a motorized damper which have a combined load of approx. 15A). I am having trouble figuring out the best way to power the fire pump controllers. Currently, the building is served from an outdoor 120/208V MDP (which serves a few building at the site) which is about 350 feet away. I am planning to bring a new 100A feeder from the MDP to a new 100A panel to be installed in the new pump room. I understand that conductors serving the fire/jockey pump controllers shall be rated per FLAx1.25 like any other motor and that the over current protection device shall be rated for the combined LRA of the motors (140+44=184 -> 200A ocpd). I am not sure whether I should:
a) Provide a 200A 3pole breaker in the new panel to serve the fire pump controller with a tap to serve the jockey pump controller. Can the panel's MCB remain 100A or does the LRAs have to be accounted for?

b) or tap the incoming feeder ahead of the panelboard (put a 50A mcb in the panel) and provide a 200A/3P fused disconnect to then serve the controllers.

Also, at the MDP, should the breaker be rated for the 100A feeder to the panel or the combined LRA of the fire/jockey pump controllers + FLA of the other equipment (so a 300A breaker)?

I apologize is this post is confusing, but any advice would be much appreciated.

Thank you!

 

[rbulsara]

a) LRA have to be accounted for all breaker/fuses in the circuit all the way back to the source.
b) tapping ahead of the main is better. In fact it would be required if you do not have a emergency generator.

NEC 695 is very clear about this, not sure where the confusion lies. The handbook is more useful than the just the code book.

Rafiq Bulsara

http://www.srengineersct.com