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Making a good ground

Discussion in 'Electronic Basics' started by LB, Feb 10, 2007.

  1. LB

    LB Guest

    I had always heard that a cold water pipe makes a good electrical
    ground. If copper, use a copper clamp and if steel use a steel clamp?
    Can copper react with steel? Seems I remember some nasty
    incompatabilities between certain metals from high school science. Can
    someone give me the basics or point me in the right direction
    regarding incompatible metals and corrosion? Thanks.
    LB
     
  2. What are you grounding and why?
     
  3. AB

    AB Guest

    The ground from my original telephone service that was done in 1933.
    I'm getting rid of that cold water pipe soon and need to move it to a
    newer pipe a few feet away. I know the telco would probably come and
    do it for free, but I hate to give up a whole day of work waiting for
    them to show up.
     
  4. Jamie

    Jamie Guest

    That way of thinking should be avoided, plumbing should not be used
    for grounding electrical devices how ever, the plumbing should be
    grounded to a real earth ground in various places but not for the
    use to allow electrical devices to connect to the pipe as a path to
    an earth ground.

    Problem 1.
    Most plumbing these days have plastic here and there and you can not
    rely on it being firmly in the ground along with soil problems.

    Problem 2.
    Plumbing should have a good earth ground connected to it, this helps
    reduce the chance of shock if one should be hanging on a faucet in the
    middle of a T-storm or standing in the tub etc..
    Also, electrical devices connected to the pipe if enter in a state of
    short can cause current to flow through fittings and end up causing
    electrical shock to others that have their hands on the plumbing else where.

    In practice, the Electrical system should have it's own earth ground
    electrode entering the sub panel where it is to be connected..

    If you are concerned about earth grounding on a device then drive an
    electrode into your ground and connect to that.
    also use appropriate ground wire., if you're in an R.F. environment and
    trying to reduce RF from riding up the ground wires? i have used a
    shielded ground made from heavy gauged coax. With that, you connect the
    braid and center together at the ground electrode, bring it into the
    location of the equipment and use only the center conductor, tape back
    the shield so that it does not come in contact with any thing on that end.
     
  5. Do Telco's ground these at the residence any more? Might be worth a phone
    call first.

    Copper or steel pipe I used a brass grounding clamp and made sure the pipe
    was really clean (emery cloth) in either case.
     
  6. ehsjr

    ehsjr Guest

    What you wrote could be taken the wrong way.
    If an electrically continuous metal underground water
    pipe exists on the premises and is in contact with the
    earth for at least 10 feet, it is *required* to be part
    of the grounding electrode system per NEC 250.50.

    I think your point is that the devices that use electricity
    should be connected to an equipment grounding conductor (EGC),
    not the cold water piping in your house. The EGC is connected
    to the electrode grounding system at the service panel. The
    electrode grounding system includes water pipes in accordance
    with the paragraph above.

    And the way of thinking that says dissimilar metals
    in contact with one another is correct - you need to
    be sure that proper metals are chosen.

    Ed
     
  7. In ancient times, when we had party lines, with selective ringing
    arranged by connecting ringers between one or the other phone wire and
    ground, you did need a ground, but I don't think that system is used
    much any more. Unless you have such an arrangement, you shouldn't
    need a ground for the phone line.


    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  8. default

    default Guest

    Cold water pipes used to make good grounds. With modern construction
    there may be plastic in the system. - inside or outside the house.

    Galvanized pipe may have bad electrical joints so should be connected
    as close to the street (service entrance) as possible.

    Don't use it for a power ground - Safer to put in a proper ground
    rod.

    1/2" or 3/4" 10 foot copper pipe with a heavy gauge wire sweated to
    it works well. If the soil isn't too rocky the pipe can be washed
    into the ground. Or just get a copper- weld ground rod and drive it
    into the ground. They don't cost much

    Dissimilar metals should be avoided due to galvanic action and
    corrosion. You can usually find grounding clamps with either copper
    plating or zinc plating for the purpose.
     
  9. default

    default Guest

    The ground on telephones these days is for the lightening arresters.
    It won't affect the operation of the phone but may save you or your
    modem from destruction.
     
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