Jockey pump transformer OCP

[gorms400]

Sorry to post another "fire pump" thread as my search pulled up quite a few, none specifically concerning my situation.

At a golf course, a fire pump for a new club house was added to an existing seperate structure, the irrigation/main pump house. This building has a 400a 480V 3ph. service. At some point, someone replaced the meter on said building with a j-box (meter was relocated to utility xfmr pad) and added a 2nd 400a fused disconnect on outside of building for the fire pump. (Hope I'm not rambling) Out of this disco we are now feeding the fire pump controller (480v, 50hp motor) and jockey pump/controller (installed as 240V, single phase). My boss already gave a price on this job/blah blah so I'm just here to do it, but we are basically tapping off the fire pump controller feed (3/0) to feed a 480V pri./240V sec. 5kva transformer, whose only load will be the 3/4hp jockey pump/controller.

My question is, do I treat this transformer as a firepump transformer per 695.5 (B) for fusing the primary and NOT fusing the secondary? Or because it's only for the jockey pump (695.1 (B) (2)) do I fuse the primary and secondary as if it were any other water pump/load?

 

[Smart $]

...

My question is, do I treat this transformer as a firepump transformer per 695.5 (B) for fusing the primary and NOT fusing the secondary? Or because it's only for the jockey pump (695.1 (B) (2)) do I fuse the primary and secondary as if it were any other water pump/load?

The latter.

 

[texie]

Sorry to post another "fire pump" thread as my search pulled up quite a few, none specifically concerning my situation.

At a golf course, a fire pump for a new club house was added to an existing seperate structure, the irrigation/main pump house. This building has a 400a 480V 3ph. service. At some point, someone replaced the meter on said building with a j-box (meter was relocated to utility xfmr pad) and added a 2nd 400a fused disconnect on outside of building for the fire pump. (Hope I'm not rambling) Out of this disco we are now feeding the fire pump controller (480v, 50hp motor) and jockey pump/controller (installed as 240V, single phase). My boss already gave a price on this job/blah blah so I'm just here to do it, but we are basically tapping off the fire pump controller feed (3/0) to feed a 480V pri./240V sec. 5kva transformer, whose only load will be the 3/4hp jockey pump/controller.

My question is, do I treat this transformer as a firepump transformer per 695.5 (B) for fusing the primary and NOT fusing the secondary? Or because it's only for the jockey pump (695.1 (B) (2)) do I fuse the primary and secondary as if it were any other water pump/load?

In my opinion 695.5(B) will apply if you elect to supply the jockey pump from the fire pump feeder. If you simply feed it from another source it would fall back to 695.1(B)(2). The key here is the code does not want the additional load of the jockey pump to infringe on the available locked rotor current available of the fire pump. If you feed it from another source this is not an issue.
I do question (I didn't do the math) if the 400 amp fusible switch is large enough to carry the locked rotor current of the 50 HP pump, let alone the addition of the jockey pump LR current. Do you realize that the 400 amp disco. may not be required at all for the fire pump as all fire pump controllers are service rated and you could route the service conductors directly to the controller ( if kept "outside" using the NEC definition)?

 

[Smart $]

In my opinion 695.5(B) will apply if you elect to supply the jockey pump from the fire pump feeder. ...

That is correct. I misread OP for my first reply, thinking the transformer was powered from ahead of the 400A disconnect.

 

[gorms400]

In my opinion 695.5(B) will apply if you elect to supply the jockey pump from the fire pump feeder. If you simply feed it from another source it would fall back to 695.1(B)(2). The key here is the code does not want the additional load of the jockey pump to infringe on the available locked rotor current available of the fire pump. If you feed it from another source this is not an issue.
I do question (I didn't do the math) if the 400 amp fusible switch is large enough to carry the locked rotor current of the 50 HP pump, let alone the addition of the jockey pump LR current. Do you realize that the 400 amp disco. may not be required at all for the fire pump as all fire pump controllers are service rated and you could route the service conductors directly to the controller ( if kept "outside" using the NEC definition)?

Thanks, I was thinking the same (for fusing the transformer) but was a bit unclear after going back to 695.1 B 2.
Thing is, inside this pumphouse is already a 120/208 panel (off of the other 400A disc./and xfmr all existing) I thought we could feed the jockey pump with, but my foreman said the jockey has to be "off the same service" as the fire pump....his words. So he wants to come off this "new" 400A disconnect for fire pump.

And 400A is close, and honestly the jockey will put it over if you use the upper end of the scale . I think that had a LRC of 30-31 IRRC and the fire pump motor comes out to 336-378, code letter is G.

Also, regardless if the disco. is required, someone already went through the effort of adding this service disconnect, I don't think we will be shutting down to change that.