How To Install Under-Cabinet Lighting: Put Brilliant Lighting Where You Work

There’s one area in the house where you’re sure to work every day — on the kitchen countertop. Here’s how you can add a touch of decorative lighting while helping to eliminate eyestrain.

Tools & Materials

Do it yourself How to install a light wall switch 300x300 How To Install Under Cabinet Lighting: Put Brilliant Lighting Where You Work

How To Install Under-Cabinet Lighting

  • Undercabinet fixtures of your choice
  • Voltage tester
  • power hand drill
  • thin-blade screwdriver
  • stiff bent wire/coat hanger
  • wire stripper
  • “plumber’s chain”
  • Electrical supplies not included with your fixtures
    • remodeling electrical boxes
    • 14-gauge Type NM (nonmetallic) cable
    • cable connectors
    • plastic cable staples
    • straps
    • wire electrical tape
    • wire nut connectors

Safety First

  • Always turn off power at its source before doing any electrical work. If you are unsure how to perform the electrical portion of this project, call in a licensed electrician. Use eye protection, dust mask and work gloves when performing potentially hazardous aspects of the project, such as drilling.
  • Always wear goggles and dust mask for protection.

Planning

In this project, we installed a series of three fluorescent fixtures under one section of kitchen wall cabinets. We chose fluorescent lights for the project because they are inexpensive, very energy efficient and produce very little additional heat. They provide all the necessary lighting to ensure that kitchen projects may be completed safely and properly.  While your kitchen may be somewhat different than ours, here are some basic planning guidelines.

Measure the depth of the valance or reveal under the cabinets. This is the piece that forms a lip at the bottom of the cabinet doors. If it’s at least 1-1/4 in., it will hide most fluorescent fixtures. Low-profile fluorescent fixtures that use a T-5 diameter lamp need only about 1 in. If you have European-style cabinets and don’t want any part of the fixtures exposed, you will need to add a valance to hide the fixture.

Measure the lengths of the wall cabinets to figure the lengths and number of fixtures you need. You can cut through cabinet sides where two cabinets meet or purchase fixtures that match up closely to the actual cabinet lengths. Most fluorescent under-cabinet fixtures are designed to be wired end to end, through the back or rear edge of the fixture. There are knock-outs in the metal housing of the fixture that are easily removed and allow for versatility when wiring. Most fixtures that use a T-5 diameter lamp come in lengths of 12 in., 18 in., 21 in., 33 in. and 42 in. so you can usually find the right length for the cabinets you have.

Important Electrical Issues

Finding a Power Source
To identify the power supply wire in a box, carefully separate the black wires (with the power switched off at the main panel) so they don’t touch each other or any other metal. Then turn the power back on and — with one lead of a voltage tester touching the ground wires — touch each black wire in turn with the other lead. The hot wire or wires will cause the tester to light up.

Circuit Capacity
To determine whether a circuit has enough capacity for the additional fixtures, add up the power (in watts) for all the electrical items and lights attached to the circuit. The easiest way to do this is to:

  • Choose one circuit and shut it off at the main panel. Then go through the house turning on lights and other electrical items.
  • Add up the wattage for all electrical items and lights that do not turn on. Most will be light bulbs, since you’ll probably be working with a 15-amp general lighting circuit. (You can identify the circuit rating by looking at the number on the circuit breaker or fuse.) But also include other things normally plugged in, like stereos and televisions.
  • Add on the wattage you intend to add for the undercabinet fixtures. The fixtures should be marked with electrical rating in frequency, voltage and amperage. Multiply the amps times the volts to determine the approximate wattage the fixtures will add to the circuit. If the total exceeds 1,440 (80% of maximum) for a 15-amp circuit, we recommend that you find another circuit.Note: The National Electrical Code (NEC) requires that you use a branch circuit for your lighting that is separate from those designated for appliances and outlets in the kitchen.

Undercabinet Runs
Whether you’re permitted to run exposed plastic-sheathed cable under the cabinets is a “gray” area in the NEC. Local agencies might have more stringent regulations than the standards of the NEC. Check with your local electrical inspector to determine the regulations for your area. You might have to run your wiring in conduit or armored cable.

Electrical Box Volume 
Electrical boxes have to be sufficiently large enough to hold all the wires and devices without overheating. To figure the minimum box size required by the NEC, 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 switch or receptacle

Multiply this figure by 2 for 14-gauge wire (2.25 for 12-gauge wire) to get the minimum box volume in cubic inches. Our new box had to have at least a 24-cu.-in. volume. Plastic boxes have their volume stamped inside.

Aluminum Wiring Warning 
If you have aluminum wiring, call in a licensed pro who is certified to work with it. Aluminum wire is a dull gray instead of the dull orange color of copper.

Installation

  • <Power source — If the wiring in your kitchen light switch doesn’t allow you to draw on a power source that’s in the existing switch box, like ours does, you may have to pull in a power supply cable from another junction box (if you’re not sure how to do this, call in a licensed electrician).
  • Wiring method — If your method is not like ours (one that runs through the basement), you may have to enter from the attic or strip off some drywall.
  • Exterior walls — Avoid running cables here, since they’ll be filled with insulation and it makes for tricky work.

Shut off the power to the kitchen light at the main electrical panel, and pull the switch from the box. Use a voltage tester to make sure the power is off, then remove the switch and the old electrical box. Label wires with masking tape to help you remember where they go.

Drill 3/4-in. holes through the floor into the center of the wall cavity directly below the switch and where the cable will feed up to the wall cabinets. Measure from pipes, heating ducts and other floor penetrations to accurately position the holes. If necessary, drive a screw through the floor (in a hidden spot) as a reference point.

Drill a 1/2-in. hole through the back of the cabinet and wall, directly behind the fixture location. For neatness, drill as close to the cabinet bottom as possible.

Push a “plumber’s chain” through the hole with a thin-blade screwdriver. Keep feeding the chain through until you’re sure it reaches the bottom of the stud cavity.

Catch the chain with a stiff bent wire or coat hanger and pull it down through the 3/4-in. hole in the floor. Hook a 14-gauge Type NM (nonmetallic) cable ground to the chain and tape it to help it snake through the holes.

Pull the cable up through the back of the cabinet, prodding it with the screwdriver to help it turn the corner.

Attach the cable to the fixture using a 1/2-in. cable clamp fastened to a 1/2-in. knockout in the fixture. Connect the wires according to the manufacturer’s directions.

Fasten the fixture to the cabinet bottom according to the manufacturer’s directions. Fasten the cable to the cabinet with a standard staple or strap.

Hang the rest of the fixtures, notching the cabinet sides where necessary. Attach them to the first fixture according to the manufacturer’s directions.

Cut the drywall to fit a larger remodeling electrical box. Then pull the new cable up from below and run both the new and old wires into the box. Attach the metal or plastic box to the wall.

Clamp the cables with the internal clamps and wire the switches according to the illustration.

Remember: If your original wiring was different from ours, or if you’re running more new cables, the connections will be somewhat different. Install the switch plate cover to complete the project.

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