How to Install Under-Cabinet Kitchen Lighting

Install and wire under-cabinet kitchen strip lighting.

By Jeff Gorton

From The Family Handyman

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Preparation

About This Project

Adding undercabinet lighting is a nearly perfect kitchen improvement project. In less than a weekend, you can add fixtures that provide bright, even light to every dim recess of your countertop. No more strained eyeballs when chopping and cooking. And you’ll love the dramatic ambience provided by halogen or xenon fixtures. Teamed up with a dimmer, these fixtures can set the mood for a romantic dinner or give off a soft glow for that midnight raid on the refrigerator.

In this article, we’ll show you a unique method of wiring undercabinet lights that eliminates disruptive wall tear-out and minimizes the difficult job of fishing cables from your attic or basement. Even though we’ve simplified the job by showing you how to easily route the cables, this is still an intermediate to advanced wiring project. Don’t try it unless you understand basic wiring techniques.

Even though the wiring is simple, you’ll still have to tie in to a source of power to provide 120 volts for the lights. We’ll tell you how to locate a suitable circuit. But if you’re uncomfortable with this part of the job, consider hiring an electrician to bring power to the junction box, and then complete the remainder of the wiring yourself. In either case, check with your local building department to see what type of electrical permit and what inspections are required.

Expect to spend a day running the flex, pulling in the plastic-sheathed cables and installing the lights. In addition to standard hand tools, you’ll need a voltage tester ($3), a wire stripper ($5), a hacksaw and a drill with both 1/2-in. and 1-1/8 in. spade bits. If you plan to mount the switch in a tile backsplash like ours, buy a glass bit ($7 to $10) for cutting the switch hole. Otherwise, a sharp keyhole saw ($8) will work for cutting the hole for the new switch as well as the access hole in the back of the cabinet. All these tools are available at a hardware store or home center.

Finding Power
There are many potential power sources, but unfortunately the electrical code prohibits any connections to “dedicated” circuits. This rules out the 20-amp small-appliance circuits in your kitchen (you can’t use the countertop outlets for power) or dining areas, 20-amp laundry room circuits and 20-amp bathroom circuits. If a light switch box has a hot, neutral and ground, you can take power from it. Other possibilities include a junction box in the basement or an outlet on the other side of the wall from the cabinets (we used a hallway outlet). Make sure there’s a protected route to get an electrical cable from your chosen power source into the base cabinets.

Even though the new undercabinet lights don’t need much power, make sure they won’t overload an existing circuit. This process is tedious and may take you several hours, but it’s a necessary step for a safe job. Here’s how you do it. To determine whether the circuit you want to use can handle the additional lights without overloading, first shut off the circuit in the main panel. Then go through the house turning on lights and other electrical items. Add up the wattage of everything that doesn’t go on, that is, everything that’s on that circuit. Then add the wattage of the lights you’ll be adding. We recommend a maximum connected load of 1,440 watts for a 15-amp circuit and 1,920 watts for a 20-amp circuit. (The circuit amperage is stamped on the breaker or fuse.) If the total wattage exceeds these amounts, find a different circuit. If you’re confused, call in a licensed electrician to help with this part.

Calculating Box Sizes
To figure the minimum box size required by the National Electrical Code, add: 1 for each hot and neutral wire entering the box, 1 for all the ground wires combined, 1 for all the clamps combined, and 2 for each device (switch or receptacle, but usually not light fixtures) installed in the box. Multiply this figure by 2 for 14-gauge wire and 2.25 for 12-gauge wire to get the minimum box volume in cubic inches. Plastic boxes have the volume stamped inside.

Finally, check to make sure the electrical box is large enough to accommodate the wires you’ll be adding. If the box is too small, replace it with a larger one.

After you’ve chosen the electrical box to tie in to, turn off the circuit breaker or unscrew the fuse that controls the circuit. Some electrical boxes contain more than one circuit. Before doing any work in the box, test all the wires with a non-contact voltage tester to make sure they’re “dead.”