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Thread: Bonding water pipes and splicing.

  1. #1

    Default Bonding water pipes and splicing.

    First of all, running #4 from 100 amp panel outside to ground rod about 15 feet away on the side of the house. Slam dunk. No problem. Inspector says good luck, call me when you’re done.

    Now for bonding the water system.

    Some conditions:

    -The main panel is in the back of the house, so it’s a pretty long run from the panel to the first 5’ of water pipe entering the house.

    -In the future, plan to move the main panel to where the ground rod is, about 15 feet from its current location.

    Some questions:

    Could the bonding wire to the water pipe be spiced mechanically when this move occurs?

    Could I cut this wire, acorn it to the water pipe closest to the current panel location, then run another wire acorned right next on the pipe and out to the new panel, so only buying like 20’ of wire instead of 60’.

    Also, since the previous home owner, put a gate valve with PVC right where the water line enters the house, I assume I need to put a “jumper” bonding wire over this short piece anyways, so thus I’m kind of using the copper pipe as a splice mechanism.

    Essentially, do I need a continuous load path with one wire for the water bonding, or could I splice with acorns and the pipe itself wherever to reach the desired water pipe in the earth coming to the property and have different pieces of wire along the pipe.

    Also, can this wire just be terminated on any screw on the neutral bar or does need it to wrap in with the main ground electrode on the neutral bar’s big screw.

    Another thing I thought of was run one “pyhsical” wire from the water pipe to the panel to the ground rod, but it really wouldn’t be able to wrap around the screw on the neutral bar, just the side of the screw since the wire continues back out the panel. Is this OK?

    Just trying to save some time and money if I move the panel in the future.

  2. #2
    Join Date
    Oct 2002


    you only need #6 to grnd rod, your not allowed splice in #4 to water system. You can put that wire under any screw on neutral bar. Only alowwed 1 wire under that screw.

  3. #3


    The first question is are you grounding or bonding the water system. If the pipe coming into your house is metal and is in the earth for 10 feet or more, it must be used as a grounding electrode. If it looks metal and you don't dig it up, the inspector will assume it is metal. If it is entirely plastic, you should be able to just bond and not ground, but I'd check with the inspector.

    The difference between grounding and bonding is that grounding wires are larger and cannot be spliced (except by welding). I'm not sure if the bonding wire can be attached anywhere to the pipe, or if it must follow grounding rules which dictate that is must be to the first 5 feet of pipe.

    If you are just bonding, you may be able to splice it, but again I'd check with the inspector. If you're worried about having to toss out a 40' wire and replace it with a 60' wire when you move the panel, you could consider buying the longer length now and running it such that the wire will only have to be shortened when you move the panel and not lengthened.

    Safest way to pass is to run a #4 from the main panel grounding or neutral bus to the water pipe. Use an open bus screw and don't try to wrap it around a big lug with some other wire.

  4. #4


    Thanks for the input, to clarify, the grounding electrode is the ground rod connected with #4. I just went with #4 since most of the tutorials on this website seem to say upsize then never have any debate issues. The cost between #4 and #6 isn’t that much. This is one continuous wire.

    I assume I’m “bonding” the water pipe. But then I guess I’m saying bonding = “supplemental ground” ? Is this true or you only “bond” the water pipe if you have another “supplemental” ground in addition to the grounding electrode. Terminology?

    The way the city residential standards read is a grounding electrode = ground rod or UFER. Then they say about “bonding” the water pipes. No mention of “supplemental” ground required.

    I do like the idea of buying the longer length now though and direct it past the future location and then around to the current location. The path would be about 70’. Then I could just clip it when the panel moves and not even have to go under the house for anything.

  5. #5


    Grounding and bonding can get confusing. If you have a metal water pipe that is at least 10' buried in the earth and coming into the house, then per NEC you must use it a grounding electrode. But the NEC realized that these are easily compromised by plumbers and future changes, so you also have to supplement it with two grounding rods.

    If the water pipe coming into the house is plastic, you have to bond the water pipes to the electrical system to remove electricity that accidently energizes the pipes (like from a failed water heater).

    The grounding electrode conductor required for 200A service is #4 and #8 for 100A service. A grounding rod does not require a wire larger than #6 regardless of your service size, but the water pipe ground has to be sized per the service size. Equipment grounding and bonding wire sizes are #6 for 200A and #8 for 100A.

    Because the bonding and grounding wire sizes are the same for your 100A service, what size of wire to use should not be an issue. Don't forget to bond your interior metal gas pipe (NEC required) and metal ductwork (NEC suggestion) if you have them.

  6. #6


    Thanks again, now it’s sinking in as I reread the articles here also. What confused me were the city standards ignoring the water pipe as the grounding electrode and adding the ground rod to start with then saying bond the water pipes. Basically, it’s already assumed something occurred to the water pipe.

    So in summary, since I have this added gate valve + some PVC pipe, maybe 12” long total interrupting the metallic pipe before enters the earth in the front yard, I’m left with all this metallic piping in my crawl space NOT IN DIRECT contact with the earth, thus “bonding” is appropriate. Also, I need not run a “a jumper” over the plastic section of pipe for any reason.

    So for bonding, I don’t believe it needs to be within that first 5’. Also, for bonding are there any issues if I should use #4(OK, I already bought some) for it? I guess I could go buy some #6(take care of 200 amp move in future) if safety is an issue.

  7. #7


    I'm still not sure I understand your pipe type. Is the water pipe from outside where it penetrates your foundation plastic or metal? If it is plastic, then there is no jumpering to do and you should only have to bond. If it is metal through the wall, then goes to some plastic pipe and valve, and transitions to metal again, then you need to ground it and jumper around this plastic interruption.

    I could see some bull headed inspector wanting you to jumper an outside metal pipe to the inside metal pipe if the PVC interruption is a short segment just through the wall. However, most should just look at the pipe coming in through the wall and assume the pipe on the other side is the same material.

    There is no problem with oversizing the grounding or bonding conductors, and it would be wise if you plan a 200A upgrade. Also, where is your water meter and are the pipes on each side of it metal or plastic?

  8. #8


    I could see some bull headed inspector wanting you to jumper an outside metal pipe to the inside metal pipe if the PVC interruption is a short segment just through the wall.
    That’s the situation I have with the location of PVC and actually the inspector was by today, and said in his eyes, with the ground rod present and the interuption of metal as it rises above the earth, just outside the house, he was satisfied with the “bonding “ application and said no need to be within the first 5 feet of pipe.

    The water meter is way out at the street and metal each side. He didn’t even address this that far out. Left it at bonding suspended pipes in the crawl space.

    Thanks again for the clarifications and advice.

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