How to install a dimmer

Installing a dimmer might look complicated, but with the right steps and a bit of basic knowledge, it’s very doable. A dimmer lets you set the perfect mood and can even save energy. Below you’ll find a clear step-by-step guide to replace a regular switch with a dimmer.

Tools you’ll need

Gather your tools before you begin so the installation goes smoothly.

- Suitable dimmer (compatible with dimmable LED)
- Voltage tester
- Screwdrivers (flat and Phillips)
- Electrical wire (if needed)
- Optional: wire connector / terminal cap (e.g., WAGO or choc block)

Safety first: Always switch off power at the consumer unit/fuse box before doing any electrical work.

Step-by-step installation guide

1. Switch off the power

Turn off the main switch or the circuit (group) for the switch you’re working on. Use a voltage tester to confirm there is no power.

2. Remove the old switch

Remove the faceplate and mechanism from the wall. Unscrew the mounting frame from the wall box.

3. Identify and check the wires

Typically you’ll find two wires:
Brown = live (feed)  |  Black = switched live (to the lamp)
Sometimes there is also a Blue neutral or a Green/Yellow earth wire (not always used by the dimmer). Wire colours can differ by country—always verify with a tester and the product manual.

4. Wire the dimmer

Connect the brown live to the dimmer’s L (line) terminal. Connect the black switched live to the dimmer’s output (often marked with an arrow or lamp symbol). Tighten terminals securely and ensure no bare copper is exposed.

5. Mount the dimmer

Neatly fold the wires back into the wall box. Fix the dimmer in place, then attach the faceplate.

6. Restore power and test

Turn the power back on and test the dimmer. If the lamp flickers or doesn’t respond correctly, the bulb may not be dimmable or the dimmer type isn’t compatible. (For LED, a trailing-edge LED dimmer is usually recommended.)

Done!

You’ve successfully installed a dimmer. Now you can fine-tune the ambiance at home and potentially extend your lighting’s lifespan.