Explanation

Lighting circuits often use a system where each lighting point is fed with a Live, Neutral and Earth (CPC). These are then extended to give the next light its Live, Neutral and Earth (CPC). Each light is then switched on & off using a switch or combination of switches that are appropriate to that lights use.

Where a light needs to be switched from two positions such as a landing light or one in a corridor it can be wired using a two way switching arrangement as demoed elsewhere in an interactive tool on Canvas. This is however limited to switching from just the two positions. If a light needs to be switched from more than two positions such as lights on a stairwell covering multiple floors or in a long corridor this may be achieved by adding a intermediate switch or switches between the two 2 way switches.

This demo shows how a intermediate switch can be inserted between 2 two way switches that have been wired with 2 switching cores between the 2 two way switches but a similar method can be used if the switches have been wired using the extend from 1 way switching to two way switching using a three core & cpc.

The insertion of an intermediate switch between 2 two way switches works by choosing between two states of operation.

• One mode allows the 2 two two way switches to connect as before by having straight through connections so L1 and L2 connections in one switch connect to the corresponding terminal in the other switch.
• The other mode crosses over so L1s in both switches connect to the L2s in the other switch.

Any number of intermediate switches can be added between the two 2 way switches provided they are wired in the same way.