How to Install Undercabinet Lighting

Turn off the electricity to the kitchen at the main electrical panel. To be sure the power is off, plug a radio into the countertop wall outlet you'll be tapping for electricity, and make sure the radio remains silent when switched on. Or you can use a lamp — and make sure it doesn't light.

Unscrew the wall plate, then disconnect the wires from the receptacle and remove it from the electrical box.

The box is nailed to a wall stud on one side or the other. Find out which by peeking between the sides of the box and the drywall.

Hold a two-gang, old-work electrical box over the existing box in the wall so the expansion of the hole is on the unattached side of the existing box — away from the stud — and then trace around it with a pencil.

After enlarging the hole, make sure the cable coming into the electrical box is loose, then use a flat pry bar to remove it.

Hold the light fixture in place and locate the prescored knockout hole in the back.

Mark the wall straight out from this "knockout" plug. Use a stud finder to see if there's a wall stud between the mark and the hole for the electrical box. If so, move your mark to the other side of the stud.

Use a ½-inch-diameter spade bit to drill through the wall directly below the upper wall cabinet.

Cut a length of 12/2 NM (nonmetallic) electrical cable long enough to reach from the ½-inch hole to the two-gang box hole, plus 24 inches.

Feed one end of the cable into the ½-inch hole bored in the upper backsplash wall.

Then gently reach into the hole where the electrical box will be installed, grab the cable end and pull it through into the kitchen.

Remove the cover and the metal socket strip that holds the bulbs from the light fixture so you have room to work.

Hold the fixture against the underside of the cabinet, then slide it forward until it's hidden behind the cabinet's front edge.

Screw it to the cabinet with the screws provided.

Use a slotted screwdriver to pry the round knockout plug from the rear of the light fixture.

Install a cable connector in the knockout hole to hold the cable in place and protect it from the fixture's sharp edges.

Strip away 6 inches of the outer plastic sheathing from the end of the cable.

Feed the cable through the connector.

Tighten the connector screws to secure the cable. Be sure the connector clamps down on the cable's plastic sheathing, not the individual wires.

Hold the new, two-gang electrical box close to the hole you cut in the backsplash wall.

Feed the end of the existing cable — the one that was attached to the receptacle — into the two-gang box.

Then pull the end of the cable coming from the light fixture into the box also. Next, push the box into the hole and press it tightly against the wall.

Note that the box has two screws, one in each diagonal corner. As you begin to tighten the screws, the box's plastic fins will flip up behind the drywall.

Continue to tighten the screws until you feel the fins pull tight against the rear of the drywall, locking the box in place.

Tip: Before sliding the two-gang box in the wall, test it to make sure the fins pop up.

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.

Take the loose end of the remaining 8-inch black wire and connect it to the black wire on the dimmer switch, using a wire connector.

Attach the dimmer's yellow wire to the black wire coming from the newly installed light fixture.

Connect the bare copper ground wire coming from the GFCI to the dimmer's green grounding wire, using a wire connector.

Connect the final white wire to the dimmer's white wire, using a wire connector.

Carefully fold the excess wires into the box, then secure the GFCI and dimmer switch with the screws provided.

Start by reinstalling the socket strip in the fixture, but don't put the bulbs in place just yet.

Inside each fixture are a white, a black, and a green wire. Connect them to the wires of the same color coming from the cable, using wire connectors: black to black, white to white, and bare copper to green.

Once the wiring is complete, add the bulbs to the socket strip and install the cover on the fixture.

Then screw on the two-gang wall plate.

Turn the power back on and test your work.

Tip: Never touch a halogen bulb with your bare hands; your natural skin oils can damage the bulb. It can also get extremely hot!

There are three basic types of bulbs used for undercabinet lighting:
fluorescent, quartz-halogen, and xenon.

Fluorescents burn cooler, use less electricity, and are more affordable; but they can hum, flicker, and produce a yellowish light. Choose a fluorescent fixture with a high-quality electronic ballast for quick starts and quiet operation, and use a cool-white bulb. Fluorescent fixtures operate at regular line voltage (120 volts).

Halogen and xenon bulbs cost more to operate and replace, but they emit a very bright white light. Halogen's light is brightest, but xenon burns cooler and lasts longer. Xenon fixtures use low voltage; a transformer steps the voltage down from 120 to 12 or 20 volts. Halogen fixtures come either way. If choosing low voltage, look for a fixture with a built-in transformer.