Guest Post: Installing a Dimmer Switch

One nice thing (among many) about having an electrical engineer for a husband is that he is quick to help me with projects involving electricity. Let’s face it, I barely made it out alive from the basic circuit class all mechanicals have to take…

We decided to install a dimmer switch for the chandelier above the dining room table. Our previous method of dimming the lights was to unscrew the bulbs (you know- 1 for a little mood lighting, 2 if things were getting really romantic). Finally, on one of our daily weekly trips to Home Depot, we picked up a switch on a whim.  I’ll let Mike take it from here with his very informative dimmer switch tutorial.

Dimmer Switch Tutorial

Adding a dimmer switch to a room is an easy way to vary the mood and save on your power bill.  For an investment of about $10 and 15 minutes you can put one in yourself.  It’s simple and you won’t need a degree in electrical engineering to get it done.  Before you start, there are a few considerations:

• Know some basic electrical safety.  Electricity can kill so understand what you’re doing before you start.
• Your local government bureaucrats may not like you doing electrical work without the help of a licensed electrician.  I once called our city office to inquire about installing some lights and receptacles in my workshop.  They wanted me to pull a permit and take a “homeowners’ electrical exam.”  I just said no thanks and headed down to Lowe’s.  They probably don’t know the difference.
• Consider this tutorial just an overview.  You should review the datasheet that will come with your dimmer switch package for more detailed instructions.

Steps

Gather materials and tools for your switch replacement.  As shown below, I have the new dimmer switch, some yellow wire nuts, and instructions that all came in the dimmer switch package.  About the only tools you’ll need are a small flathead screwdriver, utility knife, wire stripper, and maybe needle nose pliers.

Turn the switch on to for lights that you want to dim. Kill the breaker switch that controls the circuit feeding our lights.  Have a partner flip the appropriate breaker switch as you verify your lights go out.  If the breakers are not labeled very well like ours, you’ll just need to try them one at a time until the correct one is switched. It would be wise to put some masking tape over the breaker switch that kills your light circuit.  Alternately, you can put a sign over the front of the box that says “Do not operate” to prevent someone from accidentally turning it back on while you’re working.  It can happen!

Now, with the power off, remove your existing switch.  With your flathead screwdriver, remove the wall plate cover.  Unscrew the actual switch from the box that it’s mounted in.  Finally, remove all 3 wires from the screw terminals of your switch.  You’ll probably have a bare copper wire (or maybe it’s green, this is ground), two black wires (hot), and 2 or 3 white ones (neutral) that are wire nutted together.

Connect the dimmer switch to your loose wires.  My particular dimmer switch came with wire leads hanging and their ends stripped. So, all I had to do was nut them to the wires shown in the previous step.  I connected them as follows:

• One black wire (hot) on the switch to one black wire from the wall
• Another black wire (hot) from the switch to another black wire from the wall.  (Doesn’t matter which black wire from the switch goes which black wire from the wall).
• Green wire (ground) from the switch to bare wire from the wall.

Note that the white (neutral) wires are not touched.  Neutral will never be connected to any switch.

Your dimmer switch may come with screw terminals instead of the loose wire leads that were on mine.  That’s ok, just read the instructions that came with your switch so you connect the wires properly.

Pack your connected wires back into the switch box.  Then fasten dimmer switch to the box as shown below.

Install the wall plate cover over the switch.  We just reused the wall plate we had right then.  Slide the dimmer knob onto your new switch.

But then Lovely Crafty Rachael went and installed a new decorative wall plate. Turn the power back on and enjoy!

POST HIJACK! This is Lovely Crafty Rachael speaking, and I couldn’t leave you with a picture of our nasty wall plate showing 14 coats of paint. Here’s how our purdy new dimmer looks now: