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Old 02-12-2008, 12:27 AM   #1
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supplemental ground to water pipe and gas


I just replaced all the old galvy fresh water supply pipes with CPVC, or at least all the ones I could get at from the basement without tearing up walls. I now have a #4 (I think) bare stranded supplemental grounding conductor dangling from a joist. What now? There's still three sets of metal piping in the walls leading to three sets of plumbing fixtures (two baths and the kitchen). The water service is still there (copper) but it's now 20 ft from the end of the bare wire. Do I splice more wire on (ground crimp?) and run the wire all the way to the copper pipe? That pipe runs through maybe 12 ft of crawl space into which no one in their right mind would go, then underground to the meter. I just can't see much need to ground that pipe as I see no way it could ever become energized. There's also a black iron gas pipe that runs from basement wall 20' along the floor joists, then down to the furnace. Is there any reason to tie that into the ground system? Yes, I could run a new continuous wire from the panel to the water pipe to avoid the need for a splice but I'd have to tear apart walls to do it. The grounding electrode conductor proper is a bare solid wire that I can see exiitng the panel but it then disappears through the exterior wall into a concrete slab so I have no idea what's at the end. There's zero bare soil outdoors anywhere near the panel, just concrete and asphalt. Any recommendations will be appreciated.

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Old 02-12-2008, 01:00 AM   #2
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supplemental ground to water pipe and gas


According to the Code, your underground copper water main must be bonded to the electrical service within 5 ft. of where the pipe enters the building. This pipe is the primary grounding electrode for the service, not the earth ground from an unseen ground rod somewhere.

I'm assuming that you are talking about a residence. If this is a commercial installation, then you can bond the water main anywhere along it's length so long as the entire length is exposed (except where it passes through a wall from one side to the other).

All metal piping should be bonded to the ground of the electrical service. You can splice the wire, just make it the same size. Do not cover the splice up. But you are going to need to get into the crawl space and bond the underground pipe within the 5 ft. limit I described above.

As far as how the pipe would get energized, it isn't so much that it will become electrically hot from an electrical fault (though this is one reason), it is primarily the path that a lightning strike will find back to earth in the event that the building gets hit and that current travels in the electrical system. The shorter this path the better.

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Old 02-12-2008, 10:02 PM   #3
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supplemental ground to water pipe and gas


In Phase -- Thanks. Yes, it's a residence. A couple of questions still. If I am willing to assume the ground rod(s?) by the panel are just fine, then what are the rules? I have no reason to think otherwise. In fact, the stranded wire I was talking about was clamped to the water pipe system about 40 ft from where the piping enters the house (nearest soil contact). which makes me think it was intended only to bond the water piping to the ground rod(s). My reading of 250.104 is that the 5 ft rule doesn't apply, and that the splice doesn't have to be done with a ground crimp (split-bolt is ok). Specifically, it says "the bonding jumper shall be installed in accordance with 250.64 (A,B,E)." So which is it? If I regard the water-pipe as THE grounding electrode then I think I not only have to clamp it 5 ft from the wall but I also have to crimp the splice. In that case can the splice be covered up? Or if I regard the water pipe as a supplemental ground, and I use a split bolt, can I cover it up? I vaguely remember someone telling me that in general crimped splices can be covered up even on current-carrying conductors, in which case covering a crimped splice on a grounding conductor should be fine. Any help will be much appreciated as I'm a little beyond my level of expertise here.
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Old 02-12-2008, 11:49 PM   #4
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Phil look at this image and I will try to answer your questions based on it best I can.

For your situation ignore the water meter in the image.

First if a metal water pipe exists on the premises of your residence you must bond it to the service equipment grounded conductor if it is entering your home and is in contact at least for 10 feet with the earth before it enters your dwelling. The copper wire that connects to the water pipe and bonds it back to the service equipment enclosure is called your water pipe bond. It is a must do. It is sized by table 250.66 to the largest ungrounded (hot) conductor servicing your home. This is the one you see in the image that is going from the service equipment to the water pipe. The other one going to the rod electrodes is your grounding electrode conductor and it never has to be larger than #6 awg copper. Generally the run from the service equipment to the electrodes... water pipe or rod must be continuous with out splice. If you break the conductor at an electrode then You must use another clamp to go on to the next as shown with the rods in the above image. You cannot put two ends of the grounding electrode conductor under one clamp.
For services of 200 amps a #4 awg copper water pipe bond wire (electrode
conductor) is required. The table I have posted below.

Now what you have is a water pipe bond wire that is a long way from the water pipe where it enters your residence. You have a couple choices... have an inspector give you an exception (if he will) to splice that conductor and continue it on to the water pipe. In which case if he allows it you will probably be able to use a split bolt.
Your second choice would be to connect to a ground rod and run the water pipe bond wire from it the water pipe close as possible to where it enters the earth leaving the premises and as stated not farther than 5 feet. Very often your local code will require it to be closer than 5 feet. It must be sized to the table I have posted. How you get to the water pipe is your choice and if you want to dig down to it to stay out of the crawl space you can do that. It will most likely need to be in sch.40 or 80 pvc depending if you run it on the outside of the dwelling or under ground. But your clamp will need to be direct burial rated and these clamps are specific not any ole clamp like a hose clamp. I'll post an image of one. The last image is running from a ground rod (in this case concrete rebar but look at it as a rod in the earth) to the water pipe. The image sizes are for Aluminum service entrance conductors.



Table 250.66
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supplemental ground to water pipe and gas-table250.66.jpg  

Last edited by Stubbie; 02-13-2008 at 08:07 PM. Reason: changed copper to aluminum
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Old 02-12-2008, 11:50 PM   #5
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supplemental ground to water pipe and gas


250.104 applies to the bonding of metal piping, true. However, it is 250.52 that you need to refer to for the grounding electrode. If the water main serving your house is metal, and it is in contact with the earth for 10 ft or more, then is is absolutely required by code that it be used as the primary grounding electrode.

Because this is a residence, it is also required that it be connected within 5 ft. of where it enters the building.

The ground rods are required as a supplement to the water main. If the rods are buried in the concrete outside, I think you are OK, according to 250.68(A) Exception 1.

You can splice the electrode conductor that comes from your water main, as long as it is an irreversible compression type connection or exothermic weld. It CANNOT be done with a split bolt. I can be covered up.

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Old 02-13-2008, 12:24 AM   #6
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supplemental ground to water pipe and gas


Did I say split bolt...... Of course your correct but I doubt he is going to be doing any cadwelds (cost) maybe a compression splice.

Last edited by Stubbie; 02-13-2008 at 10:29 AM. Reason: added cost in the sentence
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Old 02-13-2008, 08:08 AM   #7
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I didn't see where anyone answered your question on the gas piping, maybe I missed it, but here goes.
Yes your gas piping needs to be bonded to the grounding system, but the equipment grounding conductor going to your furnace already accomplishes that task

NEC Text:
250.104(B) Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to 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 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 is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
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Old 02-13-2008, 08:28 AM   #8
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But (correct me if I am wrong) a gas pipe may not be the primary grounding electrode, i.e. it is grounded to something else (including ultimate bonding to a ground rod or water pipe), not other things grounded to it.
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Old 02-13-2008, 09:01 AM   #9
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I have a question related to the subject at hand.

My water line is PVC from a well up to the outdoor shutoff near the house. From there it is copper. The copper portion is only in the ground for a run of about 10 ft before it makes a vertical 90 turn to enter the structure.

My panel is bonded to a grounding electrode and from what I'm reading it sounds as if it should be bonded to incoming waterline as well. Do I have enough waterline in the ground for this to even make a difference?
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Old 02-13-2008, 09:07 AM   #10
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Quote:
Originally Posted by AllanJ View Post
But (correct me if I am wrong) a gas pipe may not be the primary grounding electrode, i.e. it is grounded to something else (including ultimate bonding to a ground rod or water pipe), not other things grounded to it.

Yes, your right. But the OP was asking if he had to ground the gas line along with the rest of his grounding system. The gas line is not a primary grounding electrode, it is only required to be "Bonded" to the grounding electrode system. This bonding is accomplished with the EGC run to the furnace. It's the terminology between bonding and grounding that causes the confusion. On a do it yourself site it's easier to say ground than bonding, otherwise it will take 10 posts to first straighten that out.
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Old 02-13-2008, 09:16 AM   #11
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supplemental ground to water pipe and gas


Quote:
Originally Posted by Randell Tarin View Post
I have a question related to the subject at hand.

My water line is PVC from a well up to the outdoor shutoff near the house. From there it is copper. The copper portion is only in the ground for a run of about 10 ft before it makes a vertical 90 turn to enter the structure.

My panel is bonded to a grounding electrode and from what I'm reading it sounds as if it should be bonded to incoming waterline as well. Do I have enough waterline in the ground for this to even make a difference?

Yes, if the metal water line is present and 10 feet long or more it is required to be bonded to and become part of the grounding electrode system.
250.50 Grounding Electrode System.
All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.


(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors.

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Old 02-13-2008, 10:23 AM   #12
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Thanks Silk!
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Old 02-13-2008, 10:41 AM   #13
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This thread has me thinking. What if the water line entering the structure is plastic all the way to the house, up the inside of the wall, then it converts to copper? You have no buried copper/metal pipe at all. But the dwelling is piped in copper. Are we then just bonding to an accessible spot, and where must the bond take place?

Last edited by J. V.; 02-13-2008 at 10:45 AM.
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Old 02-13-2008, 11:12 AM   #14
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supplemental ground to water pipe and gas


Like the gas pipe, the copper water pipe network with only PVC out into the earth is bonded to the electrical system (electrical system ground) for grounding purpose, not the electrical system bonded to the water pipes for grounding purposes. Here, something else namely a ground rod has to be the primary grounding electrode.

If the pipe system was not already bonded to ground such as via an electric water heater, only devices connected to a 15/20 amp. circuit receptacle have any likelihood of producing a fault to the pipe system (radio dropped in the bathtub?). Thus I am guessing that a 12 gauge bare wire is sufficient for any added ground.

Last edited by AllanJ; 02-13-2008 at 11:23 AM.
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Old 02-13-2008, 11:18 AM   #15
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supplemental ground to water pipe and gas


i don't know where you would make the bond all i know is that it must be bonded.

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