Thank you for the information!
Fire Pump Short-Circuit/OCPD
- Thread starter Canton
- Start date
- Status
Thank you for the information!
- Location
- Connecticut
- Occupation
- Engineer
- Location
- Massachusetts
So I happened to visit a friend working in a fire pump room. The sprinkler contractors had the fire pump down for testing so I took the opportunity to snap some pictures for those that do not get to see fire pump controllers.
This one has both a utility feed and a generator feed.
This one has both a utility feed and a generator feed.
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That is very similar to what I'm used to seeing with OCPD for normal and emergency. The one at my job looks the same but inside it looks like a standard ATS with no OCPD's....I will be there Tuesday and take some pictures to compare. Thanks for sharing.
- Location
- Massachusetts
No problem at all. It just worked out funny, I got done a bit early on Friday and found myself standing in front of a shutdown fire pump controller. Figured I could snap a few photos and post them.
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Do we get to nit pick? At first glance I see a few violations.
- Location
- Massachusetts
Do we get to nit pick? At first glance I see a few violations.
Go nuts, it was all inspected and approved just a few years ago.
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
The FMC and PVC do not comply with Art 695. Don't mean to nit pick, it just sort of caught my eye in the photos.
You are correct! Thanks for the catch.
Interesting turn of events today. I went to go take some pictures of the Fire Pump Controller today at the job.....and its gone. I asked the Sprinkler contractor what happened to it. Turns out that controller was for another job and their shop sent out the wrong one...:? The correct one is being sent out next week.
I asked some questions trying to get some info on make and model but the Sprinkler Fitter looked at me like i was speaking another language. I wonder if this one will come with OCPD's built in like the one posted...? I'll post some pictures when I see it.
No confusion here. The object is to have the fire pump run in a emergency until it literally melts itself into the ground. Did one recently, had to tap the main buss on a 3000 amp 480 volt service buss on the electric co side with #2 conductors feeding a 400 amp CT cabinet with a 45 amp load with 350 amp time delay fuses in the controller.
Keep in mind that many people do not exit a building when the fire alarm goes off. The fire pump must run until they decide that they have finished the file they were working on and indeed there is a fire. Then they exit.
Also many people do not maintain fire pumps like they should and many have a locked shaft at the pump due to no maintenance. the motor must break this loose and could cause a main overcurrent device to trip.
Keep in mind that many people do not exit a building when the fire alarm goes off. The fire pump must run until they decide that they have finished the file they were working on and indeed there is a fire. Then they exit.
Also many people do not maintain fire pumps like they should and many have a locked shaft at the pump due to no maintenance. the motor must break this loose and could cause a main overcurrent device to trip.
iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
- Occupation
- EE (Field - as little design as possible)
No OCPD, connected directly to the service transformer - yep.
I was involve in repairing a fire pump feeder - mid 1990s. Parallel 250kcil, maybe 750 feet, 3" rsc, 3' burial, concrete incased. Fault developed in the middle of one of the 3" rsc.
Service was 480 grnd Y, 750kva, utility owned oil filled pad mount, ug 34kv primary fed from pole outside the plant, xfm located inside the plant ~75" from the outdoor serviceequipment.
Showed up in the morning to bad electrical - looked like one or two phases out.
Called the power company, they came out and replaced the transformer 34kV primary bayonet fuses. They don't have the 10A fuses so they use 30A. Lineman turns switch on the xfm. Transformer starts rumble, smoke starts coming out of the service equipment. Lineman drops the pole he is holding for the xfm switch actuation. Runs over to truck, parked out by the pole, jumps in the bucket, goes up and jerks the cutouts open.
It was obvious which conduit had the fault. The locknuts were burned off, melted. The wire insulation from that conduit was bubbled, scorched.
Connected a boom truck to the conductors at the fire pump end and pulled until we tore them off. Pull the other end till we tore it off. Laid the conductors on the ground over the conduit path. We dug up the conduits where the 6' section was missing. Yep - burned and melted right clear though the conduit. Concrete and 2" minus backfill looked like it was trying to turn into glass.
I have no clue as to how/why the cable decided to fault after 5 years in service, in the middle of the run, in conduit, concrete incased. No backhoes, no water, didn't see any rocks in the conduit when I pulled out the wires. No obvious nicks in the insulation - at least none that I could tell were there before we pull them out with a boom truck. :?
So I am asking the fire marshal, How about we install a mag only CB for the fire pump feeder? I offered a 1200A frame, 4000A instantaneous only. In 30 years there had never been a fire that threatened the plant. The fire pump feeder failure could have taken out the whole place. I don't know where the electrical would have burned clear had the lineman not pulled the pole cutouts - I suspect when the xfm blew up
Fire Marshal said No. No OCP between the service and the fire pump controller. He absolutely understood the NEC allowed appropriatle sized OCP.
I'm still baffled as to the cause. But I think the Fire Marshal considered the failure a way-the-hell-out-there-fluke.
I'm not saying the fire marshal is wrong ..... but ....... Nah, no buts. I'm not saying he was wrong
ice
I was involve in repairing a fire pump feeder - mid 1990s. Parallel 250kcil, maybe 750 feet, 3" rsc, 3' burial, concrete incased. Fault developed in the middle of one of the 3" rsc.
Service was 480 grnd Y, 750kva, utility owned oil filled pad mount, ug 34kv primary fed from pole outside the plant, xfm located inside the plant ~75" from the outdoor serviceequipment.
Showed up in the morning to bad electrical - looked like one or two phases out.
Called the power company, they came out and replaced the transformer 34kV primary bayonet fuses. They don't have the 10A fuses so they use 30A. Lineman turns switch on the xfm. Transformer starts rumble, smoke starts coming out of the service equipment. Lineman drops the pole he is holding for the xfm switch actuation. Runs over to truck, parked out by the pole, jumps in the bucket, goes up and jerks the cutouts open.
It was obvious which conduit had the fault. The locknuts were burned off, melted. The wire insulation from that conduit was bubbled, scorched.
Connected a boom truck to the conductors at the fire pump end and pulled until we tore them off. Pull the other end till we tore it off. Laid the conductors on the ground over the conduit path. We dug up the conduits where the 6' section was missing. Yep - burned and melted right clear though the conduit. Concrete and 2" minus backfill looked like it was trying to turn into glass.
I have no clue as to how/why the cable decided to fault after 5 years in service, in the middle of the run, in conduit, concrete incased. No backhoes, no water, didn't see any rocks in the conduit when I pulled out the wires. No obvious nicks in the insulation - at least none that I could tell were there before we pull them out with a boom truck. :?
So I am asking the fire marshal, How about we install a mag only CB for the fire pump feeder? I offered a 1200A frame, 4000A instantaneous only. In 30 years there had never been a fire that threatened the plant. The fire pump feeder failure could have taken out the whole place. I don't know where the electrical would have burned clear had the lineman not pulled the pole cutouts - I suspect when the xfm blew up
Fire Marshal said No. No OCP between the service and the fire pump controller. He absolutely understood the NEC allowed appropriatle sized OCP.
I'm still baffled as to the cause. But I think the Fire Marshal considered the failure a way-the-hell-out-there-fluke.
I'm not saying the fire marshal is wrong ..... but ....... Nah, no buts. I'm not saying he was wrong
ice
- Status