How To Wire A Lighted Medicine Cabinet

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It's relatively simple to power a lighted medicine cabinet from your existing overhead light. All you need is a few tools and supplies, and confidence in your ability to work with electrical components.

What you will need:

  • Wire cutter-stripper - This tool allows you to cut a wire sheath to length, as well as strip the insulation from the ends of the individual wires within the sheath.
  • Drill - You will need to drill a hole in the wall for the electric wire to access the back of the cabinet. Drill the hole at the intended location of the light atop the cabinet, so the hole and wires won't be visible.
  • Screwdriver - You will need this to disconnect and reconnect the overhead light.
  • Flashlight - A good flashlight is always useful in electrical work, when power is off and you're in the dark or in dim light.
  • Wire nuts - These are used to secure wire connections. They resemble the caps on toothpaste tubes, and are sold in various sizes. You should buy a variety pack of different sizes for various household uses.
  • Electrical tape - This is a small roll of black elastic tape used for covering exposed wire connections and securing wire nuts in place.
  • Electric wire - Before purchasing wire, look at the circuit breaker that controls the flow of electrical current to the overhead light from which you intend to power your medicine cabinet. If the breaker has "15" printed on it, it is a fifteen amp line and will only require fourteen gauge wire. 

If the breaker has a "20" printed on it, you will need thicker twelve gauge wire. A twenty amp line handles more power, and thinner wire may become overloaded and heat to the point of starting a fire. Don't try to save money by purchasing thinner (higher gauge) wire than required.

You will need enough wire to travel across the ceiling from the light and down the wall to the medicine cabinet, but allow extra length for possible obstructions and connection purposes. Four to five meters should be enough.

Wiring the cabinet: at the overhead light

  1. First, install the medicine cabinet in its intended location, and drill the hole for the wiring. The most important step in this job is turning off the power to the light. Turn on the light before turning off the circuit breaker that controls the light. If the light goes out after switching off the breaker, you will be sure that the correct breaker was chosen.
  2. Unscrew the light mount from the ceiling, and pull the light fixture out so the wires are exposed. Remove the electrical tape and wire nuts that hold the wires together. Hold onto the light fixture when you untwist the connected wires, because it will fall otherwise.
  3. Begin to feed your wire into the hole in the ceiling in the direction of the intended location of the cabinet. When you reach the wall, you may need to jostle and wiggle the wire to force it to turn down into the wall space. When you can see the wire through the hole is the wall, pull it through until at least thirty centimeters of wire is protruding through the hole.
  4. Cut off the wire at the light and peel back the plastic sheath that holds the three individual wires within. Strip three centimeters of insulation from the end of each wire with the wire stripper, by placing each wire in the slot of the blades marked for their gauge (12 or 14) and pull it through the closed blades.
  5. Twist each of the three wires around the same colored wires inside the ceiling (black to black, white to white, green or copper colored to the same color). Twist a wire nut onto each set of connected wires until it is tight, then wrap the nut and wire ends in electrical tape to keep moisture out and keep the connection secure. Reattach the light into the ceiling.

At the cabinet

Perform the same functions with the wires from the medicine cabinet and the wire you fed through the ceiling and wall. Be sure that all connections are secure, then turn on the breaker and you're finished.

If you'd rather have a professional help you out, visit an electrician like Crown Electric Ltd.


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