How to Change a Light Switch (and When to Call an Electrician)

Short answer: Changing a light switch means turning off the breaker, testing that the wires are dead, taking the old switch out, connecting the same wires to a new switch of the same type, and putting it back. The switch itself is simple. The risk is in the parts people skip: confirming the power is really off, matching the switch type, and noticing wiring problems the old switch was hiding. If the switch is hot, buzzing or scorched, the problem is usually the wiring, not the switch, and that is a job for an electrician.

What the job involves

An electrician changing a switch does it in this order:

1. Turn off the breaker for the circuit and tell everyone in the house.
2. Test before touching. A non-contact voltage tester goes on every wire in the box, not only the switch. Switch boxes often hold wires from more than one circuit.
3. Take a photo of how the old switch is wired before disconnecting anything.
4. Check the wiring. Look at the condition of the insulation, whether the wires are copper or aluminum, whether there is a ground wire, and whether the wires were pushed into holes in the back of the switch (“backstabbed”) instead of wrapped around the screws.
5. Connect the new switch to the same terminals, with the wires wrapped clockwise under the screws and the ground on the green screw.
6. Fold the wires back, fit the switch, put the cover plate on, turn the breaker back on and test it.

On a 3-way or 4-way switch, the wires have to go to the matching terminals, not just the same positions as the old one. Copying positions from a different brand of switch is a common way to end up with a light that only works from one place. Our guide to 3-way and 4-way switches explains how they work.

Which switch to buy

Match the amp rating of the switch to the circuit as well: a standard household lighting switch is 15 amp, and a 20 amp circuit needs a 20 amp switch.

Signs the problem is not the switch

A new switch will not fix these. Stop and call an electrician if you see:

• A switch or cover plate that is hot to the touch, or a switch that buzzes, crackles or smells of burning.
• Scorch marks, melted insulation or a burnt smell in the box.
• Aluminum wiring. Silver-colored wires, common in homes built roughly from the mid 1960s to the early 1970s, need switches rated for aluminum or special connectors. Using the wrong ones is a known fire risk.
• Lights that flicker or dim when other things in the house turn on.
• No ground wire and a metal box with no ground, or cloth-covered wiring that cracks when it bends.
• A breaker that trips when you use the switch. See our guide to GFCI, GFI and AFCI protection for why some breakers trip on purpose.

When to call an electrician

Call us for any of the warning signs above, for a switch that controls a light from more than one place, for a new switch location, or for smart switches in an older home without neutral wires. In Rock Hill, the city requires electrical work in a home to be done by a licensed contractor, so a licensed electrician is the legal route there as well as the safe one.

We replace and repair switches, dimmers and smart switches across Rock Hill, Fort Mill, York County and Charlotte. We check the wiring in the box while we are there, and you get the price before any work starts.