How to Convert 2-Wire House Wiring to 3-Wire Ground

If your house is outfitted with two-prong, old-fashioned outlets connected to 2-wire cables, it is time to update the electrical system in your house. These two prong outlets don't have the ground wires, which are there to protect people and electrical devices in case of a fault.

Close-up of bare electrical wires
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How to Convert 2-Wire House Wiring to 3-Wire Ground

2-Wire Vs 3-Wire

The third prong on an outlet is typically called "the ground." The ground wire provides an alternate path for electricity that may stray from an appliance or product. Having a ground wire is very important and has been required as a safety feature since the early 1960s. Two-wire house wiring can be dangerous because it carries the risk of causing an electric shock. Three-wire electrical systems minimize the risk of electric shock. They also allow surge protectors to keep your electrical equipment safe.

The Box Must Be Grounded

You can retrofit your 2-wire outlets with new 3-wire or GFCI receptacles in the same outlet box without any rewiring. However, the box itself must be grounded.

A grounded system is one that provides a backup pathway or an alternate route for electrical current to follow back to "ground" in case there are any problems in the wiring system. If your system isn't grounded, then retrofitting a 2-wire outlet with a 3-wire outlet won't accomplish anything.

You can test to see if your system is grounded by using something called a pigtail electrical tester. These are inexpensive and available at any hardware store. The tester will have instructions that you should follow with care. There is always a danger of shock when working with an electrical system, so exercise caution and follow all instructions for the tester.

Remove Old 2-Wire Receptacles

Once you're certain that your electrical box is grounded, it's time to remove the old receptacles. First, turn off the power at the ­breaker panel or fuse box. Then, carefully unscrew the old receptacle from the box and detach the wires.

Connect the New 3-Wire Receptacles

Now, it's time to install the new receptacles. First, you must attach the black (hot) wire to the brass terminal. Then, attach the white (neutral) wire to the silver.

Next, fasten what's called the ground screw. This screw is green and sold in hardware stores. It fits into a threaded hole in the back of the box. Then, hook one end of an 8-inch green grounding wire or pigtail to the screw and tighten it. This pigtail wire is also available at your local hardware store.

The next step is to secure the other end of the 8-inch grounding pigtail to the green grounding terminal on the three-prong receptacle. Then, insert the new receptacle into the box.

Try It Out

Now, it's time to turn on the power. You can use a circuit tester to make sure the circuit is working properly. Once you've switched all of your 2-wire outlets and have a house that uses a 3-wire electrical system, you can breathe a sigh of relief. You're in a much safer home now.