04
Two-Way Switching (Staircase Circuit)
Control one light from two separate locations — the classic staircase or hallway circuit. Switch the light on upstairs, switch it off downstairs, and vice versa.
Components Needed
Text Wiring Path
Live → MCB → SW1 COM SW1 L1 ——→ SW2 L1 (strapping) SW1 L2 ——→ SW2 L2 (strapping) SW2 COM → Bulb → Neutral
Schematic
Steps
- 1Place Live, Neutral, MCB, and a Bulb.
- 2Place two Two-way Switches between the MCB and the Bulb.
- 3Wire MCB → Switch 1 COM port.
- 4Wire Switch 1 L1 → Switch 2 L1 (first strapping wire).
- 5Wire Switch 1 L2 → Switch 2 L2 (second strapping wire).
- 6Wire Switch 2 COM → Bulb.
- 7Wire Bulb Neutral → Neutral terminal.
- 8Press Run. Toggle either switch — the bulb responds from both locations.
Key insight
Two-way switching works because the two strapping wires always form exactly one complete path — toggling either switch swaps which wire is connected, turning the circuit on or off.
⚠ Safety practice
Two-way switching must interrupt the live conductor, never neutral. A switch wired on neutral leaves the lampholder live even when the light is off.
Terms used here
Defined in the glossary — each one opens at its own entry.
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