Wiring a one-gang light switch

A one-way (one-gang) light switch is the simplest switch there is. It has just two switched terminals — COM (common) and L1 — plus an earth terminal at the back box. A single twin-and-earth "switch drop" comes down from the ceiling rose: • Brown (line) carries PERMANENT live down to the switch. • The blue core carries the SWITCHED live back up to the rose when the switch is on. Because it is a live, not a neutral, it must be over-sleeved brown at both ends. • Green/yellow is the earth (CPC). Your job: terminate the three cores at the switch. The key idea: permanent live goes to COM, and the switch simply connects COM to L1 when you flick it.