Bonding two sections of copper pipe with PEX between them?

Discussion in 'Electrical Forum discussion & Blog' started by BimmerRacer, Feb 2, 2010.

  1. BimmerRacer

    BimmerRacer New Member

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    Most of the house is copper. I replumbed a portion for master bath, two hose bibs and basement bath using Uponor manifold system. I transition back to copper for the basement bath, and hose bibs.

    Do these copper segments need to be bonded back to the main supply before it first transitions to PEX? I saw something about 5' rule but didn't quite understand it.
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

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    The first five feet is if it is an electrode or if there is at least ten feet in contact with earth.

    With the introduction of the nonmetallic piping in your system there is not need to bond any part of the metal water pipe unless there is an electrode as outlined above.
  3. BimmerRacer

    BimmerRacer New Member

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    Location:
    Washington, DC
    Thank you. I recently reconnected supply to the basement bath and discovered that I get "energized" water when I turn on the vanity light switch. I verified that it's not in my hand by touching hot wire and copper pipe with electrical tester. I plan to remove drywall and look at the romex supplying that vanity light. Since nothing else has changed in terms of elecrical or plumbing in that room, could this problem have been masked by the fact that old pipes were all copper and therefore grounded? The vanity light wall box is metal and is supplied with 14/2 wire with ground. The position of the box is likely that it's touching the copper pipe, but I do not know for sure right now, until I open up the wall
  4. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Touching you meter to the hot wire and the metal water pipe and reading a voltage in no way means that your water is energized.

    What it does mean is that the hot wire is energized.

    Pure H2O does not conduct current but we all know that even distilled water has impurities and some of these impurities will conduct current. I would be expecting to get a voltage reading when reading to a water pipe if somewhere on that water pipe there is a connection back to the service. Should there be a water heater that is wired to the service the equipment grounding conductor of that circuit is more than enough to complete the path and give a voltage reading in the application you have described.
  5. BimmerRacer

    BimmerRacer New Member

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    So, I ripped out the drywall and the metal box from the vanity light was definitely touching the copper pipe. Romex wire looks fine now that the box is not touching I don't get zapped nor get any reading on the tester when I touch hot wire and the pipe.

    before and after

    [​IMG]

    [​IMG]
  6. Billy_Bob

    Billy_Bob In the Trades

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    422
    Good detective work!

    Now what was the cause?

    There should be a wire clamp on the wire going to that box which prevents the sharp metal of the box from cutting into the wire.

    Or perhaps there was a loose wire on the light fixture touching the metal of the fixture, then that was connected to the electrical box via the screws, and then to the pipe?
  7. BimmerRacer

    BimmerRacer New Member

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    There's a strain relief clamp and I had tossed the actual light fixture a few days before. *shrug*
  8. Billy_Bob

    Billy_Bob In the Trades

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    Well that's even better...

    Get a new fixture and be sure the electrical box/wires look ok, and you should be all set.

    Problem solved!
  9. Jeff1

    Jeff1 New Member

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    So Cal
    Is the metal box grounded properly? I can't tell from the picture.
  10. BimmerRacer

    BimmerRacer New Member

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    As far as I recall, the ground wire was wrapped around a grounding screw inside a the box.
  11. Billy_Bob

    Billy_Bob In the Trades

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    Good point!

    If the pipes and the electrical box were properly grounded, this would not have happened!

    Check that the metal electrical box is properly grounded, that the new light fixture is properly grounded if metal, that the ground in the wire is good, and the main electrical system grounds are ok.

    [​IMG]
  12. BimmerRacer

    BimmerRacer New Member

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    Location:
    Washington, DC
    easiest way to test for proper ground? Can I use the two probe Ideal tester? I did use it last night by touching the hot wire and the box and the result was the same as when I touched the copper pipe before, when the metal box was touching it - it showed 110V
  13. Billy_Bob

    Billy_Bob In the Trades

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    I use an ohm meter myself. This is a setting on a multimeter. Sort of like a "continuity" test, but better and more feedback/accuracy of testing method.

    If you have a long extension cord, measure the "ohms" in one wire from the plug to the outlet. Disconnected of course. You will get a certain reading in ohms and this will be low. The longer the wire, the more ohms. Then try a short extension cord and see the difference.

    So based on the length of wire, you would expect to see a certain ohms reading from one point to the other end.

    Sometimes people don't do things right and they don't bother to connect ground wires at all! So in this case, there would be no ohms reading.

    Or there may be a poor connection along the way. In that case a high ohms reading.

    The best ground system is two ground rods placed 6 ft. apart at the main electric panel.

    So what you can do to test this, is place the end of a long wire (cheap speaker wire or whatever just for testing) on one of the ground rods. Then run the wire into your bathroom, then use an ohm meter to measure the ohms from the end of that wire to the ground on the outlet. The ohms reading you get should be consistent with that length of wire (also taking into account the cheap speaker wire).

    If there is electricity present and this is shorting to ground at one end, this could wreck your ohm meter! So best to turn off the main power for this test.

    Basically you are testing that the ground wire is contiguous from that outlet box all the way to the ground rods (or cold water pipe ground if you have that).

    How to use an ohm meter...
    http://www.ehow.com/how_2282412_use-ohmmeter.html
  14. Billy_Bob

    Billy_Bob In the Trades

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    422
    P.S. You would also want to check the pipes with the long wire and ohm meter to be sure they were also properly bonded back to the main ground.
  15. BimmerRacer

    BimmerRacer New Member

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    Jeez Bob, last time I had to use Ohm's law was back...oh, longer than I can remember. :) Not sure that's the route I will go with this, but thanks for the refresher.

    I know the pipes in the bath are not bonded, and according to what jwelectric said they do not have to be. I know you said otherwise over at DIYChatroom.
  16. jwelectric

    jwelectric Electrical Contractor/Instructor

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    I have posted the proposal from the code making panel several different times so this one more time won’t matter that much.
    5-236 Log #2432 NEC-P05 Final Action: Reject
    (250.104(A)(1))
    ____________________________________________________________
    Submitter: Robert P. McGann, City of Cambridge
    Recommendation: Revise text to read as follows:
    Metal water piping system(s) that is likely to be energized , installed in or attached to a building or structure shall be bonded.
    Substantiation: With much expanded use of plastic water piping system(s) isolating section of metal piping systems. This type of installation leaves contractors and inspectors what is required to be bonded.
    Panel Meeting Action: Reject
    Panel Statement: The requirements of 250.104(A) apply to complete metallic water piping systems. Where there is no complete metallic water piping system, then the requirements of 250.104(B) would apply for those portions of isolated metal water piping system likely to become energized.
    Number Eligible to Vote: 15
    Ballot Results: Affirmative: 15

    Notice the comment about it being a complete metal water pipe system. If there is not continuity from one end to the other then the system is not a complete metal system therefore the bonding requirements for the equipment grounding conductor installed with the branch circuit is all that is required.

    As for reading the resistance between the earth connection and some point on the equipment grounding conductors is nothing short of silly.
    The equipment grounding conductor is required to be bonded to the neutral conductor of the service so a complete path back to the source is established for fault current to follow.
    The earth plays absolutely no role in the function of the circuit. There is no current trying to enter earth.
    We connect to earth for four reasons and these four reasons only. It is not to make the fuse blow or to open a breaker of any kind. It is not to allow fault current to have somewhere to go either.

    250.4 (A) Grounded Systems.
    (1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will (1) limit the voltage imposed by lightning, (2) line surges, (3) or unintentional contact with higher-voltage lines and (4) that will stabilize the voltage to earth during normal operation.

    Also read the last sentence in 250.4(A)(5)

    (5) Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems. It shall be capable of safely carrying the maximum ground-fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.

    Forget anything anyone has ever told you about the earth connection and don’t listen to anyone who tries to sell you on the idea of current flowing into the ground.

    You are supposed to get a voltage reading from the hot to any metal anywhere that is bonded to the service and also to the white or bare conductor in the circuit.
    Last edited: Feb 3, 2010
  17. Billy_Bob

    Billy_Bob In the Trades

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    422
    Well you were shocked because the pipes were not bonded to ground. Something to think about...

    Also it is not "ohms law", rather an "ohm meter". A "continuity meter" is next best.

    How to use either...
    (here used to test fuses)
    http://www.dinosaurelectronics.com/Test_Fuse.htm
    Last edited: Feb 3, 2010
  18. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Would you mind taking a few minutes and explaining how connecting anything to ground will stop someone from being shocked.
  19. BimmerRacer

    BimmerRacer New Member

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    jwelectric, what would you say the cause was and the fix should be?
  20. jwelectric

    jwelectric Electrical Contractor/Instructor

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    Location:
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    The cause of what?
    Are you saying that your water was energized due to the reading on the meter?
    Were you getting shocked?
    If you were being shocked, what else were you touching when you felt the current?
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