Step 7: Install a GFCI outlet

installing a gfci
Photo: Kolin Smith
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Join the bare copper grounding wires from both the existing and new cable with a green pigtail connector.

off the remaining cable, separate the white wire, and cut two 8-inch-long pieces. Strip ½ inch of insulation off their ends and join them to both white wires in the box with a wire connector.

Fasten the other end of one of the 8-inch white wires to the silver GFCI screw terminal marked "white-wire line."

Cut two 8-inch-long black wires, strip off ½ inch of insulation, and join them to the black wire coming from the existing (receptacle) cable.

Fasten the free end of one of these wires to "hot-wire line" GFCI terminal.

Wrap the pigtail around the green grounding screw on the GFCI, leaving at least 4 inches of wire sticking out beyond the screw.

Peel the plastic sheathingogether with lineman's pliers before screwing on wire connectors.

Tip: Twist wires together with lineman's pliers before screwing on wire connectors.
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    Tools List

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    • flat prybar
      Flat pry bar,
      to remove the old electrical box
    • Phillips screwdriver
      Phillips and slotted screwdrivers
    • drywall saw
      Drywall saw,
      to cut the hold for a new electrical box
    • spade bit
      1/2-inch spade bit,
      to bore a hole in the wall for a new cable
    • wire strippers
      Wire strippers,
      to remove insulation from wires
    • lineman's pliers
      Lineman's pliers,
      to cut and twist together wires
    • drill
      Drill/driver,
      to drive screws and bore holes

    Shopping List

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    1. Light fixture Undercabinet lights are available in fluorescent, halogen, and xenon models. We chose low-voltage halogen for its bright white light (see "10: Choosing the Light"). Measure upper wall cabinets to determine what length fixtures to buy—23 inches and 47 inches are typical sizes. You can gang them together for long runs.

    2. Dimmer switch needs to be compatible with the light fixture you choose.

    3. GFCI receptacle Once installed, this outlet’s ground-fault circuit interrupter will shut off instantaneously if you receive a jolt.

    4. Two-gang, old-work electrical box This larger box replaces the existing single-gang receptacle box in the backsplash wall. An "old work" box is for remodeling—its "fins" unfold behind the drywall to lock it in place.

    5. Two-gang wall plate

    6. 12/2 NM (nonmetallic) electrical cable plastic-sheathed cable often referred to as Romex, a trade name. The 12/2 designation refers to its two 12-gauge copper wires—a neutral and a hot. It also holds a bare ground wire. You’ll need 6 feet of cable, including loose wires you’ll cut from this for Step #6.

    7. Ground pigtail connector; cable connector; wire connectors

    8. Wood or plastic cable protector may be required by some municipalities to protect exposed cable. Make from wood or buy as "nonmetallic raceway" in 5-foot lengths.