5 Tips for Wiring a Dimmer Switch on a Fluorescent Light

a group of dimmer switches mounted on a cream colored wall
  • 4 hours
  • Intermediate
  • 200
What You'll Need
Dimmer ballast
Fluorescent dimmer switch
14/3 cable
Wire stripper
Wire cutter
Wire nuts

Having a dimmer switch on a light fixture gives you complete control. Rather than bright lighting all the time, you can adjust the light level to any setting you desire to add ambiance to a room. This is easily achieved with incandescent bulbs, and a dimmer switch will work easily with them. With fluorescent lights, however, fitting a dimmer switch is a trickier proposition. Here are some tips to get you headed in the right direction.

Tip #1 - Use Ballast


A dimmer switch won’t work with the standard ballast in a fluorescent light. You need to install a special dimmer ballast and this won’t work in all fluorescent fixtures. It’s also possible that the existing screw holes won’t work with the ballast mounting screws, in which case you’ll need to drill new holes for them. This can be a very involved procedure.

Before you begin work, check at a hardware store to be certain you can fit dimmer ballasts to your fixtures.

Tip #2 - Get the Right Cable

You can’t use the regular cable when installing a dimmer switch on a fluorescent light. Instead, you’ll have to use a 14/3 AWG cable. This has to run between the fixture and the wall switch.

You might be able to do this without tearing out the wall. Turn off the electricity for the circuit at the circuit breaker. Disconnect the wires from the fixture and attach the new wires to these loose ends. Now, loosen the wires at the wall switch and begin pulling gently. In some cases, you’ll be able to pull the wire straight through. It will take some time and won’t work if the wires are attached to the studs by staples or if they pass through holes drilled in joists or wall studs.

Tip #3 - Use the Right Dimmer Switch

You must make sure you purchase the correct type of dimmer switch as those made for incandescent lights won’t work with fluorescent lights. You need to purchase a special type of dimmer switch that’s made especially for fluorescent lights. Your hardware store will be able to give you the best advice.

Tip #4 - Be Aware of the Dangers

woman removing a light fixture from the ceiling

If you have an older fluorescent light fixture that’s not rated for dimming, don’t attempt to fit a dimmer switch. Instead, you’ll need to replace it. The same applies to any fixture with a Compact Fluorescent Lamp adapter (CFL).

If you do try to fit a dimmer switch to fixtures that aren’t compatible, you’ll overheat the lights and cause them to burn out quickly. Also, the dimmer will only operate as an on/off switch so there will be no adjustment of light available.

Tip #5 - Connect the Wiring

In the wall switch, you’ll attach the wires using the following method:

Bring the white and ground wires together with your multipurpose tool

Connect the black fixture wire to the red switch

Connect the red wire to the orange switch

Connect the black wires to the power line

You’ll need to do this before you wire up the fixture itself. To fit the fixture, you’ll need to attach the ballast wires and the wires for the dimmer switch with wire connectors. To do this, the orange wire will need to run to the red wire before you can join the white wire to the white wires, the ground wire to the ground wire, and the black to the black. Once the wiring is complete, switch the circuit breaker back on and test the dimmer switch.