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#99821 - 09/19/06 10:18 PM Cold water ground  
texassparky  Offline
Member
Joined: Mar 2004
Posts: 26
Dallas,Texas
I know this probably has been discussed many times before but here it goes again. If you don't have copper water pipe how do you ground. Do you have to drive two ground rods? The reason I ask a friend of mine is working in a town where the plumber is using Pexs "plastic" and now the town is making them use copper pipe from the water meter to the water heater so the electrician has a place to ground. Why make the plumbers do the electrican work?

[This message has been edited by texassparky (edited 09-19-2006).]


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#99822 - 09/19/06 10:53 PM Re: Cold water ground  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Running a copper pipe from the water meter to the water heater does not provide a ground for the electric service. If the water service is non-metallic, one could use the rebar of the foundation for the Grounding Electrode (Mandatory in the '05 NEC) for new construction, or a made electrode consisting of one or two rods for other than new construction. The metal pipe installed in the interior of the building must be bonded per 250.104(A) but it is not the grounding electrode.


George Little

#99823 - 09/19/06 11:20 PM Re: Cold water ground  
texassparky  Offline
Member
Joined: Mar 2004
Posts: 26
Dallas,Texas
Let me ask this if you where to put a 200 amp service on a barn its all wood dirt floors and no plumbing you would only have a 8' ground rod with a #6 connected to it correct?. We bond water pipe so in case it becomes energizer there is no hazard. So why do we have to size coldwater ground according to the service size?


#99824 - 09/19/06 11:30 PM Re: Cold water ground  
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
Has to do with the surface area contact of a ground rod versus a metal water pipe. I guess supposedly, most water pipes have more surface area contact to the ground. The larger wire increases safety. Are you megging out the ground rod?


#99825 - 09/19/06 11:42 PM Re: Cold water ground  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,103
Estero,Fl,usa
When the water pipe ground was originally used you were essentially attached to every water pipe in town. The whole city was a ground grid. At that point the ground electrode could really clear faults so it made sense to size it to the service.
These days a bolted fault to the ground electrode alone would just be a worm chaser.


Greg Fretwell

#99826 - 09/21/06 10:35 PM Re: Cold water ground  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
Quote
"If you don't have copper water pipe how do you ground?"


Ufer ground (if available).

(2) 8' Grounds if the Ufer's not available.

And a #4 copper jumper to anywhere on the copper water piping system (hot or cold). Preferrably do the grounding near the water meter as to making it easier for the AHJ to find (and see). Also, don't forget to jump out the hot & cold at the hot water heater.

[This message has been edited by ShockMe77 (edited 09-21-2006).]


#99827 - 09/21/06 11:33 PM Re: Cold water ground  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
Quote
Also, don't forget to jump out the hot & cold at the hot water heater.



Can someone tell me why it has to be at the water heater? I've had contractors tell me the inspector wants the cold and hot water pipes and the gas line all bonded together "at the water heater".


George Little

#99828 - 09/22/06 03:21 AM Re: Cold water ground  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
[Linked Image] IMO this code isnt enforced often..... Technically if the water and gas service are plastic underground, and the cold hot and gas inside are metal you need to bond them all to an electrode or main panel.

Quote
250.104(B) Other Metal Piping. Where installed in or attached to a building or structure, metal piping system(s), including gas piping, that may become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122 using the rating of the circuit that may energize the piping system(s). The equipment grounding conductor for the circuit that may energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
FPN:Bonding all piping and metal air ducts within the premises will provide additional safety.
Section 250.104(B) was revised for the 2002 Code to state that gas piping is treated exactly the same as all "other metal piping" systems within a building.


It's that "may" thats debatable. And if you can get away with doing it at the water heater - hey why not.



[This message has been edited by e57 (edited 09-22-2006).]


Mark Heller
"Well - I oughta....." -Jackie Gleason

#99829 - 09/22/06 06:40 PM Re: Cold water ground  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
Good question, George. I have to assume (I dislike using that word, alot), that the reason is because it's a common space that's easy to look for and to identify that it's been done. It's a matter of convienence in my opinion.


#99830 - 09/22/06 09:28 PM Re: Cold water ground  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
Michigan USA
I think it's because the inspect is lazy or not smart enough to understand the issues of bonding and grounding.
It would be pretty rare for the H & C water piping systems not to be bonded together via a mixing valve in a bathroom or a faucet in at a laundry tub. As for the gas line it more tan likely will be bonded via the EGC of any appliance that has electricity run to it. I'm trying to think of a gas appliance that would not have electricity run to it and drawing a blank. Maybe a gas fired pool heater??


George Little

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