Wiring Light without a Ground Wire in Electrical Box

Older Homes Frequently Lack Ground Wires in Electrical Boxes

By Mark J. Donovan

Question: Mark, I have an older light that needs to be changed and there is no ground wire in the electrical box. Do you have any advice on how to connect a new light to old wires?

Answer: DG, the lack of a ground wire in electrical boxes on older homes is a common situation. If your home’s electrical outlets are two prong chances are there is no ground wire in your electrical boxes.

Older cable either lacked a ground wire altogether or in some cases the external sheathing itself, which was made out of metal in some cases, acted as the ground.

If the electrical box that houses the wire for the old light is metal, and the cable sheathing is made out of metal, it is very likely that the electrical box is grounded via the metal sheathing. Also, if the electrical box is metal, and the cable does not include a metal sheathing it may be possible that there was a ground wire in the cable and it was attached to the back side of the electrical box.

Inspect the electrical box for this type of situation. If either of these situations is the case, just attach the new light’s ground wire to the metal electrical box.

If it appears the electrical box is not grounded, and/or metal sheathing cable is not used, then simply wire up the new light to the existing wires per the manufacturer’s instructions and leave the light’s ground wire disconnected.

Two Lights operated by One Switch

Two Lights Operated off One Switch

The light will work properly and is basically no less safe to operate. The only downside is that without the ground wire there is no protection for a circuit fault condition.

Your only other alternative is to pull new cable, which includes a ground wire, from the circuit panel box to the light and light switch. This is a lot of time and money, and updating just the circuit for this particular light doesn’t address the rest of the electrical circuits in your home.

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