Since fire pump is treated as a separate service entrance disconnect, so I guess we have to bring neutral to fire pump controller/ATS and ground the neutral there. From fire pump ats/controller to the fire pump itself (3ph motor), I don't think we need to netral wire, is this correct? Thanks!
Does fire pump need a neutral?
- Thread starter anbm
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- Connecticut
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- Engineer
Yes, that is correct, though I don't have the code in front of me to confirm the section that requires that.
The way I've always done it here, where the POCO requires the separate fire pump service to be metered, is to run to separate service to a circuit breaker & CT cabinet and ground the neutral there. From the CT cabinet to the controller/ATS, I run 3 phase conductors and no neutral.
The way I've always done it here, where the POCO requires the separate fire pump service to be metered, is to run to separate service to a circuit breaker & CT cabinet and ground the neutral there. From the CT cabinet to the controller/ATS, I run 3 phase conductors and no neutral.
Sorry, what I meant is my fire pump ats/controller is tapped off utility power transformer (on normal power side) and is fed from a generator through a panel (on emergency side), we consider the generator as a separate devrived system and ground it.
My understanding is we also have to ground the fire pump ats/controller
as well.
So the question is should we bring the neutral wire from both utility xfmr and generator panel to the fire pump ats/controller? Which mean the fire pump ats need to have 4 pole and switched neutral.
Since the fire pump is a three phase motor, fire pump contractor told me that the fire pump ats does not have switching neutral feature and we don't need a neutral wire to the ats.
What do you guys think? Do we still comply with code without neutral wire to fire pump ats? If we don't switch the neutral looks like we violate the code for grounding loop connection (I.e. At utility xfmr and generator)
My understanding is we also have to ground the fire pump ats/controller
as well.
So the question is should we bring the neutral wire from both utility xfmr and generator panel to the fire pump ats/controller? Which mean the fire pump ats need to have 4 pole and switched neutral.
Since the fire pump is a three phase motor, fire pump contractor told me that the fire pump ats does not have switching neutral feature and we don't need a neutral wire to the ats.
What do you guys think? Do we still comply with code without neutral wire to fire pump ats? If we don't switch the neutral looks like we violate the code for grounding loop connection (I.e. At utility xfmr and generator)
Volta
Senior Member
- Location
- Columbus, Ohio
To consider this a separately derived system, by definition, it must not have any direct electrical connection to the supply conductors of another system. Article 100.
Yes, I would think that you need to connect the grounded service conductor to this service disconnect/ats/FP controller. 250.24(C).
Yes, and I agree, 4 pole switch, if the grounded and grounding conductors are bonded at the generator.
Need the service neutral bonded to the enclosure. If you do not switch the neutral, you need to remove the system bonding jumper from the genset, as far as I know.
- Location
- Connecticut
- Occupation
- Engineer
I don't see any need for a 4 pole switch.
The 4 conductors from the utility transformer are run to the ATS/Controller, and the neutral is grounded as a service.
The generator is grounded at the generator as an SDS. From the generator c/b feeding the ATS/Controller, you run 3 conductors and an equipment ground. From the ATS/Controller to the pump, you run 3 conductors and an equipment ground.
There is no direct electrical connection between the supply conductors in the two separate systems.
The 4 conductors from the utility transformer are run to the ATS/Controller, and the neutral is grounded as a service.
The generator is grounded at the generator as an SDS. From the generator c/b feeding the ATS/Controller, you run 3 conductors and an equipment ground. From the ATS/Controller to the pump, you run 3 conductors and an equipment ground.
There is no direct electrical connection between the supply conductors in the two separate systems.
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Volta
Senior Member
- Location
- Columbus, Ohio
I think David is right, if the generator neutral is not brought to the ATS, then it is an SDS, and that neutral is not needed. 250.30(A)(8).
- Location
- Connecticut
- Occupation
- Engineer
You are correct, No equipment ground required from the xfmr to ATS/Controller.
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