"Ground" for Fire Pump Feeder

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charlie b

charlie b

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A fire pump is permitted to be connected to the main service panel upstream of the main breaker, and without a circuit breaker of its own. How do you size the "ground wire"? Is that ground wire an EGC, a GEC, an SSBJ, or some other type of bonding wire?
 
charlie b said:
A fire pump is permitted to be connected to the main service panel upstream of the main breaker, and without a circuit breaker of its own. How do you size the "ground wire"? Is that ground wire an EGC, a GEC, an SSBJ, or some other type of bonding wire?
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Although I do not have any practical experience with fire pumps, per 230.40 exception #5, (which sends you to 230.82(5)) These are service entrance conductors so I believe you would ultimately get sent to 250.24(C) and run a grounded conductor to the Fire pump disconnect.....Although perhaps, just like the dreaded PV supply side connection, the argument can be made that the fire pump disconnect is not a service disconnect? In which case one could use 250.92 and use a SSBJ back to the tap point? What do others think?
 
this is how i inspect the above. the pump disconnect is a service and is service rated. , the pump controller does not usually need the grounded conductor to operate but the grounded conductor is required by 250.24c. this conductor is sized by 250.24 c1 which sends you to 250.102c. since this is a service disconnect 250.24d requires a grounding electrode conductor and this is grounded like any other service
 
frank everingham said:
this is how i inspect the above. the pump disconnect is a service and is service rated. , the pump controller does not usually need the grounded conductor to operate but the grounded conductor is required by 250.24c. this conductor is sized by 250.24 c1 which sends you to 250.102c. since this is a service disconnect 250.24d requires a grounding electrode conductor and this is grounded like any other service
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(y)
 
frank everingham said:
this is how i inspect the above. the pump disconnect is a service and is service rated. , the pump controller does not usually need the grounded conductor to operate but the grounded conductor is required by 250.24c. this conductor is sized by 250.24 c1 which sends you to 250.102c. since this is a service disconnect 250.24d requires a grounding electrode conductor and this is grounded like any other service
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Just to nitpick a bit and be concise and accurate, we have the option of powering the fire pump from its own service, or having everything be one service with one additional set of service entrance conductors run to the fire pump. In the latter case, it would be wired like a service, but it wouldn't be "a service".
 
hhsting said:
I think OP means EGC size from fire pump controller to fire pump. I am not sure how to size that as well
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On the contrary, I think he is referring to the necessary ground needed at the service disconnect for the fire pump (probably part of the fire pump controller since it is service rated. He is running hot leads but no neutral from the main panel to the controller, and is asking what the required ground at that point would be considered, so he can decide where to connect it and how to size it.
 
charlie b said:
A fire pump is permitted to be connected to the main service panel upstream of the main breaker, and without a circuit breaker of its own. How do you size the "ground wire"? Is that ground wire an EGC, a GEC, an SSBJ, or some other type of bonding wire?
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A tap ahead of a the building service disconnecting means for a typical service rated fire pump controller would just need the service grounded conductor brought to the fire pump controller and bonded as these would be service conductors. The minimum size of the grounded conductor would be per Table 250.102(C)(1). The fire pump controller would be the service disconnect for the fire pump. There would be no EGC but you of course will need a GES.
As a side note these conductors would have to be outside of the building per the NEC definition and they can't be tapped in the same vertical section as the building service.
 
charlie b said:
A fire pump is permitted to be connected to the main service panel upstream of the main breaker, and without a circuit breaker of its own. How do you size the "ground wire"? Is that ground wire an EGC, a GEC, an SSBJ, or some other type of bonding wire?
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I'm not the expert on this but common sense to me would say the fire pump system would only need a grounding conductor capable of safely transporting the fault current of the fire pumps overall capable running load. Whatever the maximum draw of the fire pump is would be the grounding conductors size.
 
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Isn't it as simple as grounding a system based on the overall load at a given point of origin, whether its a 1200 A section of switch gear or a separate 60 A fire pump.
 
Another C10 said:
I'm not the expert on this but common sense to me would say the fire pump system would only need a grounding conductor capable of safely transporting the fault current of the fire pumps overall capable running load. Whatever the maximum draw of the fire pump is would be the grounding conductors size.
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Yes grounded conductors are sized to the load, however they can not be smaller than the size given in table 250.102(c)
 
If the fire pump controlller is being used as a service disconnect isn't it required to be grouped in the same location as the other service disconnects? Not in the same switchboard or switchgear but in the same location.
 
infinity said:
If the fire pump controlller is being used as a service disconnect isn't it required to be grouped in the same location as the other service disconnects? Not in the same switchboard or switchgear but in the same location.
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It has to be "remote from" the others 230.72(B). You still are subject to the nearest point of entrance requirement, so I guess you have to go under the slab/ or back outside to get where you need to go.
 
electrofelon said:
It has to be "remote from" the others 230.72(B). You still are subject to the nearest point of entrance requirement, so I guess you have to go under the slab/ or back outside to get where you need to go.
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In Charlie's case he's "tapping" ahead of the service disconnect to feed the fire pump controller. In doing so the controller (which is also a service disconnect) is still required to be grouped with the other service disconnect(s). If the fire pump is in a different room then an additional disconnect adjacent to the service would be required to provide the grouping.
 
infinity said:
In Charlie's case he's "tapping" ahead of the service disconnect to feed the fire pump controller. In doing so the controller (which is also a service disconnect) is still required to be grouped with the other service disconnect(s). If the fire pump is in a different room then an additional disconnect adjacent to the service would be required to provide the grouping.
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Rob, I dont follow the reasoning on how "tapping ahead of the service disconnect" makes 230.72(B) not apply to the tapped set and disconnect?
 
Ok I reread it a few more times, and I think 230.72(B) only applies when it is another service, not one service with multiple sets (tapping) correct? I agree with that, however looking at the fine aspects of the language in 230.71(A), only the disconnects within each set per 230.40 exception need to be grouped, so it appears a set installed per 230.40 Ex #5 does not have to be grouped, but CAN BE, unless there are already 6 "normal disconnects" there. Not sure if that is the intent but that is how I read it.
 
infinity said:
In Charlie's case he's "tapping" ahead of the service disconnect to feed the fire pump controller. In doing so the controller (which is also a service disconnect) is still required to be grouped with the other service disconnect(s). If the fire pump is in a different room then an additional disconnect adjacent to the service would be required to provide the grouping.
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See 230.72(A) Exception and 695.695.4(B)(3)(4).
 
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