Controlling a Light from Two Locations: The Two-Way Switch
A two-way switch allows you to control a single light or electrical load from two separate locations — most commonly at the top and bottom of a staircase, or at opposite ends of a long corridor. While the concept is simple, the wiring configuration differs between the UK, European, and US wiring traditions. Here is what you need to know about how to wire two-way switches in each standard.
What Is a Two-Way Switch?
A two-way switch (called a three-way switch in the United States) has three terminals instead of the standard two. In the UK, these are labelled COM (common), L1, and L2. In the US, they are labelled COM (common) and two traveller terminals (often brass-coloured).
Two-way switching requires two of these special switches wired together using a pair of traveller wires. When either switch is toggled, it changes the path of the circuit, turning the light on or off regardless of the position of the other switch.
Two-Way Switch Wiring for BS 1363 (UK)
In UK domestic installations (BS 7671), the standard two-way wiring uses three-core and earth cable (brown, black, grey, and earth):
- Przełącznik 1: Connect the live supply to the COM terminal. Connect L1 to one traveller wire and L2 to the other.
- Przełącznik 2: Connect the switched live wire (going to the light) to the COM terminal. Connect L1 and L2 to the corresponding traveller wires from Switch 1.
- The neutral wire runs directly from the consumer unit (breaker panel) to the light fitting.
- The earth wire is connected to the earth terminals on both switches and the light fitting.
Przy MORDIO, our BS 1363 switches clearly mark COM, L1, and L2 terminals for easy identification. Browse our British standard switch range for two-way options.
Two-Way Switching for Schuko (Europe)
European wiring practices are similar but use different terminology. The Schuko two-way switch (called a Wechselschalter in German) works on the same principle but often uses:
- One common terminal (usually marked L or P)
- Two traveller terminals (marked 1 and 2, or the up/down arrows)
European installations often use a 4-wire cable (live, neutral, switched, earth) or separate traveller wires depending on the specific wiring tradition in each country.
Three-Way Switching (US Terminology)
In the United States, what the UK calls “two-way” is called “three-way” switching. The wiring is:
- Connect the hot (black) supply wire to the common terminal of Switch 1
- Connect the two traveller wires between the traveller terminals of Switch 1 and Switch 2
- Connect the switched hot wire from the common terminal of Switch 2 to the light fixture
- Neutral (white) wires connect directly between the panel and the light
- Ground (green or bare) wires connect to all devices
Widzieć MORDIO’s American standard switch range for NEMA-compatible three-way switches.
Typowe błędy, których należy unikać
- Using standard one-way switches: Two-way switching requires specifically designed two-way switches — standard one-way switches have only two terminals
- Incorrect terminal identification: Always verify which terminal is COM — wiring the traveller to COM instead of the incoming supply will not work
- Mixing up colours: Take photos before disconnecting old switches, and label wires clearly during installation
For Three or More Locations: Intermediate Switching
If you need to control a light from three or more locations (e.g., both ends of a corridor plus a middle switch), you need an intermediate switch (four-way switch in the US) wired between two two-way switches. The intermediate switch swaps the traveller connections, effectively inverting the circuit each time it is toggled.
Streszczenie
Two-way switching is a practical solution for multi-location light control. While the wiring principle is universal, always follow your local wiring regulations and switch terminal markings. For high-quality two-way switches in all major standards, explore Asortyment produktów MORDIO.
