Interactive diagram + guide

Dimmer switch wiring diagram

Replacing a switch with a dimmer? Choose the dimmer type to see which lead connects where, then flip it on the diagram.

Buying a smart switch? Check if your box has a neutral wire first.

Tool

Interactive dimmer switch wiring diagramThree steps: pick your setup, flip the switches, wire it

Step 1 of 3

Which setup do you have?

Look in the box with the breaker off: what matters is where the power cable comes in. Pick the one that matches, or keep the one already selected.

Step 2 of 3

Flip the switch

Tap a switch, button or GFCI on the diagram. Glowing wires are carrying power right now. On a small screen, scroll the diagram sideways.

Show power flow

Black: hot
White: neutral
Red: hot / traveler
White + black tape: hot
Bare copper: ground
Wire nut
Glow: carrying power now

Use a dimmer rated for LED bulbs (often labeled C•L or LED+), and keep the total bulb wattage within its rating.

Step 3 of 3

Wire it box by box

Safety first. Turn off the breaker and confirm the power is off with a non-contact voltage tester before touching any wire. Follow your local electrical code; some areas require a licensed electrician or a permit. If you find aluminum wiring, cloth-covered wiring, scorched insulation or more than one circuit in a box, stop and call an electrician.

Switch box

Grounds: join the bare copper wire in the 14/2 cable bringing power in, the bare copper wire in the 14/2 cable to light box and the dimmer’s green ground lead under one wire nut.
Neutral splice: join the white wire in the 14/2 cable bringing power in and the white wire in the 14/2 cable to light box under one wire nut.
Dimmer, dimmer lead 1 (either black lead) → the black wire in the 14/2 cable bringing power in.
Dimmer, dimmer lead 2 → the black wire in the 14/2 cable to light box.

Light box

Light fixture, black lead → the black wire in the 14/2 cable to switch box.
Light fixture, white lead → the white wire in the 14/2 cable to switch box.
Light fixture, ground lead or screw → the bare copper wire in the 14/2 cable to switch box.

Guide

Standard vs. smart dimmers

A standard single-pole dimmer wires exactly like a switch: incoming hot to one lead, the light to the other, plus ground. It doesn’t use the neutral. Most smart dimmers need a neutral wire to power their Wi-Fi or Zigbee radio, plus a LINE lead for incoming power and a LOAD lead to the light.

Choosing a dimmer for LED bulbs

Pick a dimmer rated for LED bulbs (often labeled C•L or LED+).
Check the minimum and maximum LED load. A dimmer driving one or two low-watt LEDs may flicker below its minimum.
Use a dimmable LED bulb. Non-dimmable LEDs buzz, flicker or fail early on a dimmer.
Side-by-side dimmers in one box have lower ratings once their side fins are removed. Check the instructions.

3-way dimming

With a basic 3-way dimmer, only one location dims and the other end stays a regular 3-way switch. To dim from both places, use a multi-location dimmer with the companion from the same brand.

All dimmer switch setups

What you need

LED dimmer switchSingle-pole and 3-way capable, rated for LED and incandescent bulbs.
Check price
Smart dimmer (neutral required)Wi-Fi dimmer for boxes with a neutral wire.
Check price
No-neutral smart dimmerFor switch boxes without a neutral.
Check price
Non-contact voltage testerConfirms the power is really off before you touch a wire.
Check price

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Frequently asked questions

Does a dimmer switch need a neutral wire?

Standard dimmers don’t. Most smart dimmers do, although some no-neutral models exist, such as Lutron Caséta. Use our neutral wire checker.

Why do my LED lights flicker on a dimmer?

Usually the dimmer isn’t LED-compatible, the bulbs aren’t dimmable, or the load is below the dimmer’s minimum. Many LED dimmers have a trim adjustment for the low end.

Can I use a dimmer on a ceiling fan?

No. A light dimmer can damage a fan motor. Use a fan-rated speed control for the fan and a dimmer only for the light kit.

Is it normal for a dimmer to feel warm?

Slightly warm is normal. Hot to the touch, a burning smell or buzzing means the dimmer is overloaded or failing: turn it off and replace it.

Dimmer switch wiring diagram

Which setup do you have?

Flip the switch

Wire it box by box

Switch box

Light box

Standard vs. smart dimmers

Choosing a dimmer for LED bulbs

3-way dimming

All dimmer switch setups

What you need

Frequently asked questions

More wiring tools