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  • Wiring question

    Hello everyone,

    My parents own a house that was built in about 1972. All of the wire used for electrical was either done with EMT conduit in the basement or flexible metallic conduit in the rest of the house. The ground for the electrical system is provided by EMT conduit and flexible metallic conduit.

    Now, I know this is not allowed today but if an older house is wired like this does one have to upgrade the wiring so that the conduit isnt the main grounding conductor for the electrical system? Or, would the electrical be grandfathered in say if you were going to sell the house?

  • #2
    Re: Wiring question

    Originally posted by Palomino View Post
    Hello everyone,

    My parents own a house that was built in about 1972. All of the wire used for electrical was either done with EMT conduit in the basement or flexible metallic conduit in the rest of the house. The ground for the electrical system is provided by EMT conduit and flexible metallic conduit.

    Now, I know this is not allowed today but if an older house is wired like this does one have to upgrade the wiring so that the conduit isnt the main grounding conductor for the electrical system? Or, would the electrical be grandfathered in say if you were going to sell the house?
    As long as it was done to code at the time of installation and has not been altered since it does not have to be changed. When selling a house there is often no requirements of the electrical system. You could sell the house with nothing meeting any code whatsoever. Getting someone to buy said house is the issue.

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    • #3
      Re: Wiring question

      If the EMT hasn't been broken or disrupted in any way the continuity of the grounding conductor via conduit should be fine. The length of the run can be a factor.

      For example: 1/2 inch EMT can be used up to 231 feet to be an effective grounding conductor and 3/4 EMT goes a bit farther to 246 feet. this is from Soars Book on Grounding.

      This is based on a clearing ground-fault current of 500 percent of overcurrent device rating; circuit 120 volts to ground.

      So as long as the conduit is in good condition there shouldn't be any problem at all.

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      • #4
        Re: Wiring question

        Palomino

        You may not have access to all of them, but be sure the connectors are secure and any screws in them are tight, but don't go wild and overtighten them.

        If you're worried about grounding you could have a green grounding conductor pulled through the EMT but normally this isn't necessary. In many older commercial buildings they rely on EMT and/or greenfield as the grounding conductor. Personally I don't like it that way. If a connection isn't good you have a void.

        When you refer to flexible metallic conduit this might be what's known as BX <aka> armored cable. About what is the outside diameter of most of it?

        Is your family wanting to sell this house or are you worried about having good grounding? An electrician can run tests to insure good low resistance grounding throughout the house. You might not like the $$$ for it but it should be a good bit less than doing upgrading work.
        Last edited by Woussko; 11-04-2007, 08:36 PM.

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        • #5
          Re: Wiring question

          useally with the EMT's if properly secured and tighten down there is no issuse with the grounding at all.

          if you feel need extra protection you can run green THHN/THWN wire with proper sized in the conduct and termated the green wire at each box that will even help some more.

          Merci, Marc

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