adding ground to old circuits


Old 10-09-01, 04:28 PM
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My house was wired before ground wires were used so all the outlets are 2 plug. I want to update to grounded outlets. How do I add ground wires to the existing circuits or do I have to completely rewire.
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Old 10-09-01, 11:21 PM
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rewiring is your #1 best option. option #2 might be to install GFI breakers to the two-wire circuits and grounding receptacles to this.
Old 10-11-01, 06:21 AM
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For general purpose use, you might consider what wirenuts suggested. The NEC permits you to replace 2-prong receptacles with 3-prong providing all the 3-prong non-grounded receptacles are GFCI protected. Each must also bear a label that reads "No Equipment Ground". This is an NEC requirement.

You can protect a whole string of receptacles by wiring through one GFCI receptacle that feeds downstream receptacles. You can also protect a whole circuit by installing a GFCI next to your breaker panel, pulling the wires of the circuit you wish to protect out of the panel, attach them to the "load" terminals on the GFCI, then run new wires from the breaker and neutral bus to the "line" terminals on the GFCI. If there is any short or other ground fault anywhere on that circuit the GFCI will trip.

If you insist on having a ground wire at your receptacles that's OK too. Especially if you have a true surge protector, such as for a computer circuit. They don't work without a true ground. Short of replacing your existing cables with grounded romex, you can run a ground wire parallel to the existing cable and connect it anywhere on your "grounding electrode conductor", or to the ground bus in your panel. Do not connect a ground wire to your plumbing anywhere other than 5 feet from the water main's point of entrance to the house, and always on the street-side of the meter, unless you have a proper jumper around the meter. Attaching ground wires anywhere else on the plumbing system is forbidden by the NEC in dwellings, as it can energize your faucets, bath tub, etc.

If decide to run ground wires you should follow the path of the existing cables. I would recommend running #12 copper wire with green insulation. Running bare wire outside of a cable is generally a bad idea.

One note, not that I think you're contemplating it, but there are those who think bonding the neutral to the grounding terminal on the yoke of the receptacles is a good way to ground the receptacle, thinking that since grounds and neutrals terminate on the same bus in your main breaker panel it's all the same. It isn't. It is forbidden, and it is dangerous.

Hope that helps.


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