Light Dimmer Switch Installation

By Mark J. Donovan

A light dimmer switch is a must have if you’ve just installed a home theatre in your family room. A light dimmer switch is also a great way to add ambiance to you dinning room.

Light Dimmer Switch installation is fairly easy for a homeowner to do. All that is required are some needle nose pliers, a couple of screw drivers, wire strippers, a volt meter or neon light tester, and about 1 hour of your time.

Step 1: Turn of power to the switch at the electrical panel.

Step 2: Check that power is indeed of at the switch. Toggle the switch to make sure the light is off.

Step 3: Remove the faceplate cover.

Step 4: Using your voltmeter or neon tester, probe the light switch terminals to see if the light switch is truly powered off.

Step 5: Disconnect the electrical wires from the switch and straighten them with you pliers.

Step 6: If installing a new light dimmer switch with only two black wires, install the new light dimmer switch by connecting the two black wires on the dimmer switch to the wires coming out of the electrical box. Note that there is no polarity with a 2 black wire type light dimmer switch, so it doesn’t matter which black dimmer wire attaches to which light switch wire.

Step 7: Twist each pair of wires together and attach a wire nut over each pair.

Step 8: If the light dimmer switch has a green wire (ground wire), connect this wire to the ground wire in the electrical box.

Step 9: If installing a light dimmer switch that has black and red wires, connect the black wire to the power (Line) and the red wire to the (Load).

Step10: To determine which is the Line and which is the Load, pull out both switch wires from the box and separate them. Also pull out the ground wire if the light switch is installed in a plastic electrical box.

Warning: Be careful that you separate the wires from each other first. Have someone turn on the circuit breaker to the light dimmer switch. Use a voltmeter or neon tester to see which wire is the Load and which one is the Line. The wire that causes the Voltmeter to deflect, or the neon tester to light, is the Line wire. Be careful not to touch the bare wires with your body.

If the electrical box is metal, probe one switch wire and the metal box, and look for a deflection on the voltmeter, or the neon tester to glow. Again, if you do see a deflection or if the neon tester glows, then this is the Line wire.

Now that you know which is the Line wire, have someone turn off the circuit breaker before proceeding to connect the light dimmer switch wires to the Line and Load wires.

Step 11: Connect the wires by twisting each pair together and installing a wire nut over them.

Step 12: Push the newly wired light dimmer switch into the electrical box and secure it with the two mounting screws.

Step 13: Install the light dimmer switch faceplate cover.

With the light dimmer switch installation complete, turn the power back on to your new light dimmer switch and test it.

For information on Changing a Light Switch, See HomeAdditionPlus.com's "How to Change a Light Switch Ebook". It provides detailed, easy to understand, step-by-step instructions and pictures, on how to replace a Light Switch.