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Ground Wire

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  • Ground Wire

    I'm replacing 50 year old shielded wire with Romex 12/3 (ground included) in a small section of 1 circuit (1 outlet, 1 switch, 1 fixture.) This replacement does not go back to the panel. I'm attaching the bare copper ground wire to the green screws on the new outlet, switch and fixture. I assumed this would carry the ground continuously from the boxes containing the outlet or switch back to the ground at the panel. A three-light, plug-in tester says I have a "open ground." Does this need to be resolved? How did old houses without conduit and 2 prong outlets provide a ground?

    Thanks,
    BGC

  • #2
    Re: Ground Wire

    There was no ground circuit on the 2 prong outlets in most cases. If the wire from the panel feeding the first circuit where the new wire begins only has 2 wires (black and white) you will need to run back to the panel with new wire to pickup ground

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    • #3
      Re: Ground Wire

      The energized line for this circuit should be in one of the three boxes that comprise the circuit you are working on. The wire that provides power to the circuit is probably in a metal box. This is where the BX from the panel ends. In that box, and all boxes in the circuit, the switch, outlet or fixture should be connected via a ground wire to the box in which it resides. Customarily, "pigtails" are used. A wire is connected to the box using a green gound screw in a box. All switches, outlets or fixtures also in that box are then connected to that pigtail. Remember, the metal shielding in "old" style BX cable is the ground "wire" in an armored cable system. That's why transitions from BX to Romex must be made in a metal box. The shielding, when clamped to the box, provides the ground to that box. Any Romex wires leaving that box need to have their ground wires machanically connected (screwed using a green gounding screw)to the same box. Check to make sure your shielded wire and romex grounds are continuous and you should not have an open ground.
      there's a solution to every problem.....you just have to be willing to find it.

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      • #4
        Re: Ground Wire


        What I have, in a lot of the boxes, is the BX coming into the box but, not clamped, just hanging lose and stripped back to expose the black and white wires. I assume I should find a way to attach it.

        The exterior, waterproof, reddot fixture I have attached to this switch has a Romex ground wire on a green screw at the base of the lamp holder. There is no ground connection in the lamp fixture box other than the 2 screws that hold it together and, anyplace the bare wire may be touching the housing. There is a neoprene gasket between the cover with the lamp and the housing. Are 2 screws enough metal/metal ground contact?

        Thanks,
        BGC

        Comment


        • #5
          Re: Ground Wire

          BGC

          Working with the jacket on BX takes a bit of effort and being careful. There are BC connectors which you need. They look much like Romex connectors but have a cylinder (short) sleeve with a screw in the side. In older work the steel jacket served as the grounding conductor. Because this did pose safety issues, today BX comes with a bare copper wire that's connected along with the outer jacket to ground at all points. One thing you can do because this is old work would be to run a green #14 or #12 wire beside the BX and strap it on. Connect and use that for grounding. This needs to go back to your load center (fuse box or breaker panel) and then to each work box. You want to be 1000% sure of having a good ground everywhere it's needed. Never second chance or assume things regarding safety.

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          • #6
            Re: Ground Wire

            Don't forget you need anti short bushings for all the BX ends to prevent the wires from being cut by the armor

            Comment


            • #7
              Re: Ground Wire

              Good point, Wayne

              Around here they used to be called "Red Eyes".

              Comment


              • #8
                Re: Ground Wire

                You mentioned the electrical box that you picked up the feed for your Romex ONLY had the BX wire cut off and the BX coming through the box hole with no clamp fixing the armour cable tight to the metal box. THIS IS WHY YOU ARE SHOWING NO GROUND UPON TESTING. Whoever wired the house, HOPEFULLY did not use BX cable throughout the house without using clamps to clamp the BX to the metal boxes. If that is the case, even if you clamp the BX in that box and there is another box with connections before it, your ground would be broken there. When you transit from BX to Romex, you bond the bare wire of the Romex to the metal box with a green screw, from there you can use plastic boxes or metal. If you use metal boxes with Romex, you MUST bond the box first, by doing so, you use a green bonding screw wrap the bare ground wire from the Romex around the screw and then use the remaining wire to attach to the outlet ground, this way the box and the outlet are both grouned well. In the case of the "red dot" box, you also ground that box with the green screw and the bare wire from the Romex, then usually the light fixture cross bar that screws to the box in turn the fixture screws to that and gets grounded. IF the fixture has separate ground wire, attach that to a pig tail of ground wire with a wire nut.

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