What a double switch is and why you might replace one

A double light switch (also called a dual switch) has two separate switches side by side in a single wall plate. Each switch controls its own light or outlet independently. You replace one when a switch stops working, feels loose, won't stay in the on or off position, or has a cracked toggle. Replacing it is a straightforward job that takes about 15 minutes once you turn off the power.

The switch itself is inexpensive — usually $2 to $5 — and the work requires only a screwdriver and a voltage tester. You do not need an electrician for this task, though you should call one if you are unsure about the wiring or if the switch controls a 240-volt circuit (like an electric range or dryer).

Key Takeaways

  • Turn off power at the breaker and test the switch with a voltage tester to confirm the power is off before you touch any wires.
  • Take a photo of the wire connections before you remove the old switch so you can reconnect them in the same spots on the new one.
  • Most double switches have two brass screws (hot wires), two silver screws (neutral wires), and one green or bare screw (ground wire).
  • Push the new switch straight into the box and tighten the screws gently — over-tightening can crack the switch or damage the wires.

Turn off the power and test for safety

Go to your breaker panel and flip the breaker that controls the double switch to the off position. If you are not sure which breaker it is, turn it off and have someone flip the light switch to confirm the lights go out. Once you have the right breaker, flip it back on and leave it on for now.

Go back to the switch and use a voltage tester (a battery-powered tool that costs $10 to $20 at any hardware store) to touch both the brass screws on the switch. The tester should show no power. Then touch the silver screws. Still no power. Now turn the breaker off again and leave it off — this is your working state. Test the switch one more time with the voltage tester to be absolutely sure there is no power. If the tester lights up or beeps, do not proceed; call an electrician.

Remove the old switch and photograph the wires

Unscrew the two screws that hold the switch to the wall box — one at the top and one at the bottom of the switch body. Gently pull the switch straight out of the box. Do not yank it; the wires are still connected.

Before you touch anything, take a clear photo of the wires and which screws they are attached to. This is your reference for putting the new switch in. You will see wires attached to the brass screws (usually two of them), the silver screws (usually two of them), and possibly a green or bare copper screw (the ground). Write down or photograph which wire color goes to which screw.

Now loosen each screw by turning it counterclockwise until the wire falls free. Work one wire at a time so you do not mix them up. Set the old switch aside.

Connect the wires to the new switch

Take your new double switch and look at the screws. You will see two brass screws on one side, two silver screws on the other side, and one green or bare screw at the bottom. The brass screws are for the hot (power) wires, the silver screws are for the neutral wires, and the green or bare screw is for the ground wire.

Using your photo as a guide, insert each wire into the correct screw hole and tighten the screw clockwise. Tighten just enough that the wire is snug — you should not be able to pull it out by hand, but you should not need to strain. Over-tightening can crack the switch body or damage the wire insulation.

If you have a ground wire (green or bare copper), attach it to the green screw. If there is no ground wire in your box, that is normal for older homes; leave the green screw empty.

Push the switch into the box and find it

Carefully push the switch straight into the wall box. The wires should fold neatly behind it. Do not bend the wires sharply or cram them in — they should fit with gentle pressure. Once the switch is flush with the box, insert the two mounting screws (top and bottom) and tighten them hand-tight. Again, do not over-tighten.

Screw the cover plate back on and turn the breaker back on. Test both switches to make sure each one controls its own light or outlet. If either switch does not work, turn the breaker off again and check that all wires are seated firmly in their screws.

When to call an electrician

Call an electrician if the voltage tester shows power even after you flip the breaker off — this means the switch is on a different circuit than you thought, or there is a wiring problem. Also call if you find more than two wires attached to the brass screws on one side of the switch, or if the wires are a color you do not recognize (like orange or red). These situations usually mean the switch controls something more complex, like a three-way circuit or a 240-volt load.

If the new switch works but the lights flicker, dim, or behave oddly, turn the breaker off and check that all wire connections are tight. If tightening does not fix it, call an electrician — the problem may be in the circuit itself, not the switch.

Frequently Asked Questions

Can I replace a double switch with two single switches?

Yes, if your wall box is large enough. A double switch takes up the same space as two single switches side by side. You will need to separate the wires and connect them to two separate switch bodies, then install them in a dual-gang box. Take a photo of the old switch first so you know which wires go where.

What if the wires are not color-coded or I cannot tell them apart?

Take a photo before you remove the old switch, and label each wire with a piece of tape as you disconnect it. Write "hot 1," "neutral 1," "hot 2," "neutral 2," and "ground" on the tape. This removes all guesswork when you connect the new switch.

Do I need to turn off the breaker if I am just replacing the cover plate?

No. The cover plate is plastic and does not touch any wires or metal parts. You can remove and replace it with the power on. But if you are replacing the switch itself, always turn off the breaker and test with a voltage tester first.

What if one side of the double switch works but the other does not?

Turn off the breaker and check that the wires on the non-working side are tight in their screws. If they are tight and it still does not work, the switch may be defective. Replace it with a new one. If the new switch also does not work, the problem is likely in the circuit wiring, and you should call an electrician.