Make a Christmas Tree Dimmer Switch

med bright tree 5596-2After years of debate, dead needles, and adamant kids (“It has to be real or it’s not Christmas!”), we finally broke down and bought an artificial tree. The cost of a fresh fir has gotten out of hand (and they sure didn’t last very long in our dry climate), plus our kids and their husbands had their own places, and could make their own fake-or-fresh decisions.

We looked long and hard to find a tree that looked as real as possible, and I’m happy to say that it fools many people. Even better, it came with the lights already integrated into the branches. No more tangled strings of lights, with all the reds in a clump and whole sections of tree dark. No sirree, things would be easy now.

bright lights 5595-1The kids came to help us assemble the tree and hang the ornaments. Everyone remarked on how lifelike our fir was. In fact, all was going well indeed—with nary a complaint about selling out—until we plugged the tree into the wall. Yikes! We were blinded by a zillion tiny white lights. You could see our tree from down the block. You could see our tree from orbit.

All the ornaments we’ve collected over the years—the handmade clothespin angels, the painted tin from our Mexican vacation—were so many dark blobs among all that glare.

We all turned to my husband and said, “Do something!” So he did.

finished dimmer 5598 (2)Not only will Pete’s “Christmas tree dimmer switch” save your eyeballs, it will also save your light bulbs. By turning down the voltage by 5%, and thus reducing the light output a mere 20%, you more than double the life of the bulb.* In fact, we never turn the lights on more than about three-fourths of the way. That’s plenty of brightness. It would be a nightmare trying to replace the lights on our tree. Hopefully, we’ll never have to.

Caveat 1: We have not tested this on LED lights. It might work, but they are dimmer and long lasting to begin with, so you probably wouldn’t need this.

Caveat 2 (courtesy of our liability insurance attorney): If you electrocute yourself, and/or burn the house down, or in any other way mess up, we are not responsible.

*Voltage, light output, and lifetime

Parts List

  • Power cord, grounded (3-prong) for safety. You can make this by cutting off the end of an extension cord (not the prongs—the other end, with the slots)
  • Standard wall outlet
  • Rotary dimmer switch
  • box and switch 5601-1Two-gang electric box (one that holds two switches or outlets, the blue box in the photo)
  • One orange wire nut (the orange cap in the picture)
  • Dual outlet cover for electric plug plus dimmer


Wire cutter (if power cord doesn’t already have bare wires at one end)


  1. DSCF5601-1Push the power cord’s cut end through one of the openings in the back of the blue box
  2. Tie a knot in the cord (so it stays put) about six inches from the end, and yank on it so the knot is snug against the inside of the box
  3. Prepare the cut end of the power cord (if necessary) by exposing four inches of each of the three wires inside and a half inch of bare wire at the ends of the wires.
  4. You should now have green, black, and white wires sticking out from the end of the power cord, each with a little bare wire at the end.
  5. DSCF5601-2Attach the green power cord wire to the green lug on the outlet. This is the ground.
  6. Attach the white power cord wire to any of the silver side screws (there are usually two) on the outlet.
  7. Attach the black power cord wire to one of the black dimmer wires, using the orange wire nut. To do this, put the two wires next to one another in parallel, and screw the wire nut over the ends. Tighten. There should be no bare wire visible! If there is, you made the bare part too long. Trim it a little and try again.
  8. Attach the dimmer’s other black wire to the brass side of the outlet.
  9. switch 5600-1Jam the outlet and the dimmer into the blue box and screw them down. Leave the screws a little loose so you can adjust them a little to fit the outlet cover.
  10. Screw on the outlet cover.


  1. Turn off the dimmer.
  2. Plug the cord into a wall outlet.
  3. Are your house lights still on?
  4. Turn on the dimmer.
  5. Are your house lights still on?
  6. Plus in an incandescent (not a CFL, as they are not dimmable) lamp into your dimmer. Does the dimmer work?
  7. Plug your Christmas tree in, pour some eggnog, and relax

3 thoughts on “Make a Christmas Tree Dimmer Switch

  1. I found a REALLY nice substitute for this the last time I was at Home Depot. Leviton now makes an extension cord with built in slide dimmer switch! Less than $10 in either black or white, 300 watts. Google TBI03 to find it. At HD it’s in with the regular dimmer switches.
    (I believe this will also allow you to convert a desk task lamp to use dimmable CFL bulbs. Most desk lamps don’t come with a dimmer switch… this fixes it!)

    • That’s the ground. If there is a green lug to connect it to, use that (see step 5). If not, don’t worry about it. You can’t ground anything to plastic anyway.

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