1-Way Switching

1-way switching is the simplest switch arrangement — one switch controls one light from one location. It's what most domestic lights use. With a modern 3-plate loop-in ceiling rose the lamp lives on the rose, and a single 2-core+E switch drop connects to the switch.

Inside the Switch

A 1-way switch is a single-pole single-throw (SPST) device — just an on/off contact between two terminals. The terminals are usually labelled COM (common) and L1. When the lever is up the contact arm bridges COM and L1, completing the circuit; when it's down the arm lifts away and the circuit breaks.

Wiring Diagram

Following the Current

1. Permanent live leaves the consumer unit and enters the rose's loop terminal.
2. From the rose's switch terminal, the 2-core+E switch drop carries perm L down to the switch. Brown lands on COM.
3. With the switch closed, the internal contact bridges COM and L1.
4. L1 sends switched live back up the second core of the same cable (blue, sleeved brown) to the rose's switch return input.
5. Inside the rose, the switch return feeds the pendant terminal, which sends switched L down the pendant flex to the lamp.
6. Neutral travels straight from the rose's neutral plate down the pendant flex to the lamp — it never goes near the switch.

Opening the switch breaks step 3, so the lamp loses its switched L and turns off.

Cables Required

Sleeving Rule

The blue core in the switch drop carries live whenever the switch is on, so it must be sleeved brown at both ends — at the rose's switch-return terminal and at the switch's L1 terminal. Treat it as a live conductor, never as a neutral.

There is no neutral at the switch in this arrangement. Smart switches that require a neutral cannot replace a standard 1-gang switch on this wiring without running an additional cable.