UK switch & dimmer wiring guides
2-way, intermediate, and dimmer wiring for UK homes – in accordance with BS 7671:2018 (the IET Wiring Regulations, 18th Edition).
UK switch and dimmer wiring guides from Samotech, in accordance with BS 7671:2018 (the IET Wiring Regulations, 18th Edition).
How-to guides
- How to wire a 2-way light switch (UK)
- How to convert a single light switch to 2-way (UK)
- How to wire a switch to a dimmer (UK)
- How to wire an intermediate switch (UK)
- How to wire a double light switch (2-gang) (UK)
Wiring diagrams
Understanding the basics
- UK lighting cable colours explained – brown/blue/green-yellow, the 2006 harmonisation, twin-and-earth vs three-core-and-earth, and BS 7671 sleeving rules
- 1-way vs 2-way switch: what’s the difference? – terminal count, internal wiring, and when to use each
- Leading edge vs trailing edge dimmer – which dimmer technology pairs with which bulb type, and why getting it wrong causes buzz and flicker
- Dimmable bulbs UK guide – difference between dimmable and non-dimmable LED bulbs, Power Factor (above 0.9), and compatibility with trailing-edge dimmers
- What is a potentiometer? – standard dimmer potentiometers vs the rotary encoders inside the SM323 series, and what each one enables
Adding a dimmer to a 2-way circuit
If you’re upgrading one of the 2-way switches to a dimmer, see the Samotech rotary dimmer switch range – designed for UK 2-way circuits without a neutral at the switch position (the standard UK lighting topology).
Standard UK dimmer switches
Trailing-edge dimming for LED loads. No-neutral wiring. Fits a standard UK back box.
If you also need smart control (Alexa, Google Home, Apple Home, Home Assistant, app dimming, schedules), the SM323 range adds Zigbee, WiFi, or Matter to the same no-neutral wiring: SM323 Zigbee, SM323-WF WiFi, SM323-MT Matter.
About these guides
Written by Samotech, the UK manufacturer of smart switches, dimmers, and lighting controls. Wiring guidance is in accordance with BS 7671:2018 (the IET Wiring Regulations, 18th Edition).