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How to determine the ground wire

  1. Aug 14, 2008 #1
    I am about to install an electric outlet . There are three wires to and I am not sure which
    one is the ground wire . All wires having the same color !
    How can I determine which one is the ground ?
  2. jcsd
  3. Aug 14, 2008 #2
    If the installation is in the USA it does not meet the requirements of NEC.

    The only way I know of to determine without doubt which is the ground wire is to ring them out and mark each wire. The ground wire and the neutral wire will both display extremely low resistance to an earth ground as they are bonded together at some point (if the installation is properly done).

    Make sure all the wires are de-energized and then trace them out from the outlet box back to their source; disconnect all three and use a bell ringer or continuity checker to identify each wire and marke them "H", "N", "G" for "hot", "neutral" and "ground".

    Unless the original outlet was a dedicated circuit to that location only, the wires likely are connected to other outlets. If you can determine that a nearby outlet is also connected to those wires, you can check continuity from the terminals of that outlet to the ends of the wires are the location you are going to install the new one. Just make sure the power is off before you touch the bell ringer to the wires. Here again, you may become confused when you find that two of the wires will ring to the ground post...this is because they are connected together back at the panel board. That's why it helps to disconnect all three at the panel before ringing.

    Another solution would be to get up off the wallet and call a qualified electrician.
    If you don't understand the problem, you should not try to fix it. You may start a fire or be seriously injured. Electrical arcs can result in serious burns or fires because the arc temperature can exceed 4000 degrees F.
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