Question

Draw two wiring diagrams of the dual control switch, both diagrams showing the combination turned ON.

Answer 1

(i) S₁ at a, S₂ at a' — ON

(ii) S₁ at b, S₂ at b' — ON

The bulb lights in both diagrams because the levers of S₁ and S₂ touch the same connecting wire (a–a′ in one, b–b′ in the other). This closes the circuit from live to neutral through the bulb. If the two levers touch different wires, the circuit stays open and the bulb goes OFF.