Intermediate Switching

Intermediate switching extends 2-way switching to three or more locations. An intermediate switch is inserted between the two 2-gang switches to create an additional control point.

Wiring Structure

SW12-wayINT4-termSW22-way→ lampIntermediate switch bridges strapping wires

The Intermediate Switch

An intermediate switch has four terminals (L1, L2, L3, L4). It crosses-over or passes-through the strapping wires depending on its position:

  • Position A: L1→L3 and L2→L4 (straight through)
  • Position B: L1→L4 and L2→L3 (crossed)

This allows any one of the three switches to change the light state regardless of the others.

Cable Requirements

  • SW1 to INT: 3-core T&E
  • INT to SW2: 3-core T&E
  • All non-brown cores used as live must be sleeved brown

Practical Considerations

Intermediate switches cost more and are less common than 2-gang switches. For three-location control (e.g. long hallway with three doors), they are the correct solution. For more than three locations, additional intermediate switches are inserted in the chain.