Fire pump service grounding
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Re: Fire pump service grounding
Three pole Or Four Pole Transfer switch??
See definations Seperately Derived Systems.
If 4 pole ground at Main Service and at generator. If 3 pole ground only at the Service.
I take it you go from generator Breaker To transfer switch and Service Panel to the transfer switch (Listed for fire pump 695.10)
Three pole Or Four Pole Transfer switch??
See definations Seperately Derived Systems.
If 4 pole ground at Main Service and at generator. If 3 pole ground only at the Service.
I take it you go from generator Breaker To transfer switch and Service Panel to the transfer switch (Listed for fire pump 695.10)
Re: Fire pump service grounding
Thanks for the reply yoopersup.
Let's assume 3pole transfer switch.
My contention is that the fire pump service would be treated like any other service and subject to all the usual rules regarding grounding, bonding, grounding electrode conductor, grounding electrodes, etc.
Let's also assume that the fire pump service from the utility pad mount transformer is separately routed outside the building from the "normal" service and the fire pump service disconnect (combination disconnect/ATS)is 200' from the "normal" service disconnect. Normal service is 2500 amps. Fire pump service is 1/0 CU. Even though the fire pump has no neutral connected load, the grounded conductor must be run from the pad mount transformer to the fire pump service equipment (utility grounds the pad mount transformer).
Thanks for the reply yoopersup.
Let's assume 3pole transfer switch.
My contention is that the fire pump service would be treated like any other service and subject to all the usual rules regarding grounding, bonding, grounding electrode conductor, grounding electrodes, etc.
Let's also assume that the fire pump service from the utility pad mount transformer is separately routed outside the building from the "normal" service and the fire pump service disconnect (combination disconnect/ATS)is 200' from the "normal" service disconnect. Normal service is 2500 amps. Fire pump service is 1/0 CU. Even though the fire pump has no neutral connected load, the grounded conductor must be run from the pad mount transformer to the fire pump service equipment (utility grounds the pad mount transformer).
Re: Fire pump service grounding
Your point about ground loops is interesting, I'd like to know your ideas on that. FYI, the two GECs will probably bond together at the water service.
[ April 01, 2005, 10:24 PM: Message edited by: ga77 ]
Yes, single owner, single building. The grouping would apply to the 2 to 6 disconnects for each service (2 separate groups since we have 2 services). In our case we have one disconnect for each service, or possibly 2 on the fire pump when you include the jockey pump.
Your point about ground loops is interesting, I'd like to know your ideas on that. FYI, the two GECs will probably bond together at the water service.
[ April 01, 2005, 10:24 PM: Message edited by: ga77 ]
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Fire pump service grounding
ga77...the code would allow a separate GEC from each service disconnecting means to the metal water pipe. I'm not sure what concern benaround has with ground loops?
Also,you could run a common grounding electrode conductor from the main building disconnect to the water pipe based on the size of the 2500 amp service entrance conductors which would be 3/0 copper GEC, unless specified of a larger size by plan design. Then tap off the common GEC and run a #6 copper to the fire pump service disconnecting means. The location of the metal water pipe service would influence this method.
Note that the 2005 NEC requires the additional disconnecting means for a fire pump to be remote from the normal building service disconnecting means...230.72(B) and 695.4(B)(2)
shortcircuit2
ga77...the code would allow a separate GEC from each service disconnecting means to the metal water pipe. I'm not sure what concern benaround has with ground loops?
Also,you could run a common grounding electrode conductor from the main building disconnect to the water pipe based on the size of the 2500 amp service entrance conductors which would be 3/0 copper GEC, unless specified of a larger size by plan design. Then tap off the common GEC and run a #6 copper to the fire pump service disconnecting means. The location of the metal water pipe service would influence this method.
Note that the 2005 NEC requires the additional disconnecting means for a fire pump to be remote from the normal building service disconnecting means...230.72(B) and 695.4(B)(2)
shortcircuit2
Re: Fire pump service grounding
shortcircuit2: I don't believe you can tap off the 3/0 with a #6 to the fire pump service since the #6 to the fire pump is also a GEC and must be run continuous to a grounding electrode. In our case the domestic water service should be close to the fire pump. I'm not sure if we have dissimilar metals for the sprinkler service and interior piping so I'm not counting on using that. I understand that the multiple GECs are allowed but if ground loops are encountered I believe the Code would allow relief. I'm interested in anyone's opinion on the possibility of ground loops.
shortcircuit2: I don't believe you can tap off the 3/0 with a #6 to the fire pump service since the #6 to the fire pump is also a GEC and must be run continuous to a grounding electrode. In our case the domestic water service should be close to the fire pump. I'm not sure if we have dissimilar metals for the sprinkler service and interior piping so I'm not counting on using that. I understand that the multiple GECs are allowed but if ground loops are encountered I believe the Code would allow relief. I'm interested in anyone's opinion on the possibility of ground loops.
shortcircuit2
Senior Member
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- South of Bawstin
Re: Fire pump service grounding
ga77...you had my nose in the book for a good part of the day about the use of a common grounding electrode conductor for multiple services to a building.
The NEC doesn't seem to specifically address the use of a common GEC for separate services, but does allow it for multiple separately derived systems, and for services with multiple disconnect enclosures.
Actually I didn't see anything that would disallow the use of a common GEC for multiple services to a building...
shortcircuit2
ga77...you had my nose in the book for a good part of the day about the use of a common grounding electrode conductor for multiple services to a building.
The NEC doesn't seem to specifically address the use of a common GEC for separate services, but does allow it for multiple separately derived systems, and for services with multiple disconnect enclosures.
Actually I didn't see anything that would disallow the use of a common GEC for multiple services to a building...
shortcircuit2
Re: Fire pump service grounding
If you have a 4 pole switch grounding is required for Generator service and Service panel. Since Neutrals are broken at the transfer switch. If you use a common ground for both, your defeating the puropse of the 4 pole switch by tieing the neutrals together again thur the grounds!!The Idea of a 4 pole is to keep them completely Seperate.
If you have a 4 pole switch grounding is required for Generator service and Service panel. Since Neutrals are broken at the transfer switch. If you use a common ground for both, your defeating the puropse of the 4 pole switch by tieing the neutrals together again thur the grounds!!The Idea of a 4 pole is to keep them completely Seperate.
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Fire pump service grounding
yoopersup...ga77 said to assume a 3-pole transfer switch...
shortcircuit2
yoopersup...ga77 said to assume a 3-pole transfer switch...
shortcircuit2
Re: Fire pump service grounding
ga77,
shortcircuit2 is correct with the GEC tap,I to have had my nose in "the book" and it seems to me that you have 'one' service.
Follow these articles to confirm.
230.2 ex.2 ; 230.40 ex.2 ; and 250.64 d
The concern I had was with the GFPE on the 2500a main,seeing the neutral/grounding connetion coming from the fire pump GEC.I'm still not sure on this so my input is NFG.
Good luck with the project!
frank
ga77,
shortcircuit2 is correct with the GEC tap,I to have had my nose in "the book" and it seems to me that you have 'one' service.
Follow these articles to confirm.
230.2 ex.2 ; 230.40 ex.2 ; and 250.64 d
The concern I had was with the GFPE on the 2500a main,seeing the neutral/grounding connetion coming from the fire pump GEC.I'm still not sure on this so my input is NFG.
Good luck with the project!
frank
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Fire pump service grounding
benaround...ga77 does have 2 separate services as defined by article 100...
GFPE is for AC grounded services 1000amps or more operating at more than 150 volts to ground...
ga77... I sniffed it out, 250.24(A) does specify that a GEC be installed for each service...
IMO...a GEC tap off a common grounding electrode conductor connected to a common grounding electrode system should be allowed in a building with multiple services that are allowed according to 230.2(A) through (D)
shortcircuit2
benaround...ga77 does have 2 separate services as defined by article 100...
GFPE is for AC grounded services 1000amps or more operating at more than 150 volts to ground...
ga77... I sniffed it out, 250.24(A) does specify that a GEC be installed for each service...
IMO...a GEC tap off a common grounding electrode conductor connected to a common grounding electrode system should be allowed in a building with multiple services that are allowed according to 230.2(A) through (D)
shortcircuit2
Re: Fire pump service grounding
Shortcircuit2: I believe your right on all counts except the IMO. I think each GEC must be run to a common grounding electrode system.
I don't have my 2005 code book with me, this is based on 2002, which I don't believe is materially different here.
See if you (or anyone else) agree with this reasoning:
250.24(C)says the GEC is used to connect to the grounding electrodes.
250.58 talks about separate services connected to grounding electrodes.
250.64(C) says continuous.
250.64(D) "taps" applies to a single service with multiple service disconnects only.
250.64(F) says GEC... run to any ... electrode.
Therefore, I think each GEC must be run to an electrode and not spliced to a common GEC.
Shortcircuit2: I believe your right on all counts except the IMO. I think each GEC must be run to a common grounding electrode system.
I don't have my 2005 code book with me, this is based on 2002, which I don't believe is materially different here.
See if you (or anyone else) agree with this reasoning:
250.24(C)says the GEC is used to connect to the grounding electrodes.
250.58 talks about separate services connected to grounding electrodes.
250.64(C) says continuous.
250.64(D) "taps" applies to a single service with multiple service disconnects only.
250.64(F) says GEC... run to any ... electrode.
Therefore, I think each GEC must be run to an electrode and not spliced to a common GEC.
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Fire pump service grounding
ga77...I do agree with you about 250.24(A) and the 2002 NEC requirement for a continuous GEC from each service to the electrode system.
2005 250.64(C) NEC now recognizes the use of an accessible busbar as a splice or juction point to interconnect grounding electrode bonding jumpers with the grounding electrode conductor from the service. A specific location or a limit on the number of busbar connection points is not spelled out.
Now, all services to a building must use the same electrode system. I don't see a difference between the busbar configuration and my opinion of allowing the use of a properly sized common grounding electrode conductor with a properly sized tap off the common grounding electrode conductor to additional services within a building,except the allowed use of the busbar complies with the NEC.
Isn't the GEC just a flexible extension of the grounding electrode in theory?
jus thinkin out loud...
shortcircuit2
ga77...I do agree with you about 250.24(A) and the 2002 NEC requirement for a continuous GEC from each service to the electrode system.
2005 250.64(C) NEC now recognizes the use of an accessible busbar as a splice or juction point to interconnect grounding electrode bonding jumpers with the grounding electrode conductor from the service. A specific location or a limit on the number of busbar connection points is not spelled out.
Now, all services to a building must use the same electrode system. I don't see a difference between the busbar configuration and my opinion of allowing the use of a properly sized common grounding electrode conductor with a properly sized tap off the common grounding electrode conductor to additional services within a building,except the allowed use of the busbar complies with the NEC.
Isn't the GEC just a flexible extension of the grounding electrode in theory?
jus thinkin out loud...
shortcircuit2
Re: Fire pump service grounding
shortcircuit2:
I just don't see it.
There is a big difference between a GEC and an electrode.
I think for safety reasons that the GEC is REQUIRED to be run to a grounding electrode. It's not just a rule but something that makes sense.
At least the GEC must actually be CUT to disconnect it from the grounding electrode system.
The spliced bus bar situation only apllies to ground bars inside equipment or around electric rooms. You would never see bus bars extended beyond here. I really don't think the code had multiple splicing of bus bars through a building in mind when they wrote this.
Bottom line is that each service requires an unspliced GEC to a grounding electrode. Except for the allowed spicing of bus bars which we all know occurs only in spliced ground bus within switchboards or electric rooms and does not extend beyond.
shortcircuit2:
I just don't see it.
There is a big difference between a GEC and an electrode.
I think for safety reasons that the GEC is REQUIRED to be run to a grounding electrode. It's not just a rule but something that makes sense.
At least the GEC must actually be CUT to disconnect it from the grounding electrode system.
The spliced bus bar situation only apllies to ground bars inside equipment or around electric rooms. You would never see bus bars extended beyond here. I really don't think the code had multiple splicing of bus bars through a building in mind when they wrote this.
Bottom line is that each service requires an unspliced GEC to a grounding electrode. Except for the allowed spicing of bus bars which we all know occurs only in spliced ground bus within switchboards or electric rooms and does not extend beyond.
shortcircuit2
Senior Member
- Location
- South of Bawstin
Re: Fire pump service grounding
ga77...A busbar may be used out side of a electric room or anywhere in a building as long as it is accessible. This bus bar may be used as a splice point for the ground electrode conductor(s) and grounding electrode(s) serving the building...
See 250.64(C)(3) 2005 NEC
I agree that sections of busbar spliced to form an GEC don't extend out of the electric room usually, but only because it would be difficult to install beyond the electric room, not because the code restricts its use beyond the room.
Now, my opinion and theory are just that
shortcircuit2
ga77...A busbar may be used out side of a electric room or anywhere in a building as long as it is accessible. This bus bar may be used as a splice point for the ground electrode conductor(s) and grounding electrode(s) serving the building...
See 250.64(C)(3) 2005 NEC
I agree that sections of busbar spliced to form an GEC don't extend out of the electric room usually, but only because it would be difficult to install beyond the electric room, not because the code restricts its use beyond the room.
Now, my opinion and theory are just that
shortcircuit2
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