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Thread: Jumper Wire over Water meter?

  1. #1
    DIY Member jdon88's Avatar
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    Default Jumper Wire over Water meter?

    I noticed there is an old wire connected to the main water pipes on either side of the meter. What is its purpose, continuity for grounding electrical? Meter body looks like its metal. Its ugly and I'd remove it if not necessary, or replace with new wire. Thanks.

  2. #2
    Nuclear Engineer nukeman's Avatar
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    It is for electrical grounding. The water pipe is being used as a ground rod and that jumper is in place to ensure that there is still a connection to the "ground rod" when the meter has been removed for repair/replacement.

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    Senior Robin Hood Guy Ian Gills's Avatar
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    It used to be a requirement in my area but it no longer is now. So mine was removed.

    Local codes vary and, it would appear, change as well.

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    Moderator & Master Plumber hj's Avatar
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    As a practical matter, if the water pipe is metallic to the water meter, it has already had plenty of contact with the earth so that jumper is strictly cosmetic. And if the pipe is not metallic, then the jumper performs no function either.

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    DIY Senior Member Fubar411's Avatar
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    My understanding is it is not for electrical grounding (well, at some time it was), but to electrical bond the pipes. Although, I can't imagine a scenario where just that little nub of pipe is electrified.

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    Plumber jimbo's Avatar
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    The jumper is to ensure that the path to ground is not interupted when the meter is removed. I have heard...not seen personally....about plumbers getting knocked stiff in such cases....the house pipe was hot!

  7. #7
    Nuclear Engineer nukeman's Avatar
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    No, it is for grounding. See NEC 250.52 (2008 edition). This section talks about grounding electrodes. A metal underground service pipe can serve as a grounding electrode as long as it is at least 10ft in length. You are also required to bond to this pipe within 5ft of where it comes into the building. The main reason for this requirement is so that is someone replaces a section of the water pipe with plastic, they won't cut off the grounding path. Also, if it is within 5ft of where it comes into the building, people are likely to see it if they were to replace the pipe where it come in or if they were going to replace the pipe out to the street with non-metalic pipe.

    The other common way to ground is with 8ft long grond rods driven into the ground, but there are a couple other options as well.

    250.53 (D) (1): says that continuity of the grounding path or bonding connection to interior piping shall not rely on water meters or filtering devices or similar equipment (meaning you need the jumper across the meter).

    In addition, NEC currently wants a 2nd electrode installed unless you can prove that the resistance to ground is less than 25 ohms with your single rod. This is usually more trouble than it is worth, so it is easier just to drive two ground rods or use a single ground rod in addition to the water pipe (assuming metal and >10' in length).

    If you want to check the NEC for yourself, you can view it here: http://nfpaweb3.gvpi.net/rrserver/br...NFPASTD/7008SB

    Pretty much everywhere in the US uses the NEC. They may use older editions, but likely going to be some version of the NEC. The only way that I can see of you getting rid of the jumper would be to not use the water pipe as a grounding electrode and drive two rods instead. You still need to bond the metalic water piping (for a different reason), so you wouldn't be better off. If you want to make it pretty, go to HD or Lowes and grab a couple new grounding clamps and a foot or two of new bare copper wire. I don't think that anyone is looking at your meter and thinking it could be decorated better, though.

    hj: I'm pretty sure we are talking about a meter that is installed in the house and not one at the street.

    EDIT: There are two issues. 1). the metal water pipes (and similar) are bonded to the ground/neutral buss bar in the panel. This will cause the breaker to open if a hot wire were to contact the water piping. 2). This piping is serving as the ground rod in this case. The ground rod normally doesn't do a thing, but helps to protect against lightening, high voltage transients, etc.
    Last edited by nukeman; 08-31-2010 at 02:29 PM.

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