What is this copper wire under the kitchen sink?

Discussion in 'Electrical Forum discussion & Blog' started by RandomS, Sep 22, 2008.

  1. RandomS

    RandomS New Member

    Messages:
    9
    I moved into my house about nine months ago, so I'm still discovering interesting new things. :)

    I was doing some work under the kitchen sink, and I noticed a thick stranded copper wire coming up into the cabinet through the hole that the plastic drainpipe passes through. It looks like the same kind of wire that's used to ground an electrical panel -- several thick uninsulated copper wires twisted together -- but it's not connected to anything under the sink.

    I went and looked at the electrical panel, and it looks like the other end of this wire goes into the panel on the top side. The bottom of the panel has a similar wire that runs outside the house and down into the ground.

    So what's the wire doing under my kitchen sink?
  2. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    How old is the house?

    Keep in mind that anyone could have done electrical work on the house including past homeowners, so no telling what you will find, especially in old homes. Also other workers come along and do things.

    Anyway it could be that someone at one time might have connected a cold water pipe ground as well as ground rod(s) outside. Then maybe a plumber (or homeowner) needed to fix the sink and removed the connection from the cold water pipe and never reconnected it.

    Or maybe metal water pipe was replaced with plastic pipe and it was pointless to keep a connection to the cold water pipe.

    Or maybe an electronics type had a ham radio and wanted a good ground inside and had a wire run from there to his ham radio.

    Or maybe it is an old house with two wires and no ground and someone wanted to ground the garbage disposal or dishwasher.

    All sorts of possibilities!
  3. RandomS

    RandomS New Member

    Messages:
    9
    The house was built in 1986, and all of the circuits are grounded.

    There is no garbage disposal, and the dishwasher is wired up to a grounded circuit.

    It looks as if this wire was installed when the house was built, since it runs through the joists above a finished ceiling. That's just a guess, though.

    Should I connect this wire to the copper cold water supply pipe?
  4. Billy_Bob

    Billy_Bob In the Trades

    Messages:
    422
    Before doing anything, I would dig up the ground wire going underground and see where it went. Then I would trace the wire under the sink and see where it went.

    And I would look in the panel (with the main power off) to see what ground wire(s) were there. Note: EVEN WITH POWER OFF, LIVE POWER IS PRESENT IN A MAIN PANEL! BEST FOR ELECTRICIAN TO DO THIS!!!

    Then I would learn if the main water pipe was plastic or metal, and learn if the water meter isolated the water line from the street water line with rubber grommets.

    Then learn what the local electrical code was for grounding an electrical service in my area.

    Then bring my electric service grounding up to code (if it was not). I would probably connect the cold water pipe ground outside, not inside. (Again depending on the situation.)

    So I would not just connect the wire to the water pipe without knowing about everything else in the electrical and plumbing system.

    Note: If there is an electrical malfunction and you have one hand on a ground wire and another on a water pipe, you could be electrocuted! (With system not properly grounded.) So in certain situations it could actually be dangerous to connect a ground wire to a water pipe!

    Best to call an electrician if you are not sure about any of the above.
  5. RandomS

    RandomS New Member

    Messages:
    9
    We actually have a well, not town water.

    Sounds like I'll be talking to an electrician on this one. Thanks!
  6. Thatguy

    Thatguy Homeowner

    Messages:
    1,460
    Location:
    MD
    If you run a light bulb from the wire to a known good ground and the bulb lights or burns out this wire carries potentially lethal current.
  7. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    It is likely your water bond that has been disconnected by a plumber.
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