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.

The simplest switching arrangement is the one way lighting system where a cable usually a twin & CPC is taken from the light fitting to the switch and is common for rooms only having a single entry point such as bathrooms and bedrooms

We will now look at how a light can be switched from two different positions such as a landing light or one for a corridor. There is more than one way of wiring a light to be operated from two different positions. This demo will now look at the way in which and existing one way switched light can be altered to switch it from an additional position. This is slightly more complex than you might think at first as its not just adding another 1 way switch in series with the existing as its functionality would be limited. For example if switch 1 was on switch 2 could switch the lamp on or off, and similarly if switch 2 were on switch 1 could switch the light on or off, BUT if both switches were off neither could switch it on by themselves. We NEED to wire it so need either switch can turn the light ON or OFF irrespective of the state of the other. Starting with an existing light fed by a 1 way switch we do the following.

• Run a new 3 core & cpc cable between the new and old switch positions.
• Connect the original cpc to the new 3 core & cpc'c cpc together in the back boxes earth terminal and or switch cover (if metallic) using earth sleeving to cover both bare cores to the termination point(s).
• Remove the brown (live) and blue with brown sleeving (switched live) from the existing 1 way switch.
• At the original switch position, take your new 2 way switch and connect the original twin and cpc's brown and the black of the new 3 core & cpc to terminal L1 remembering to put a piece of brown sleeving over the black core.
• At the original switch position, connect the original twin and cpc's blue and the grey of the new 3 core & cpc to terminal L2 remembering to put a piece of brown sleeving over both of these conductors.
• At the original switch position, connect the brown of the new 3 core & cpc to the Common or terminal C.
• At the new switch position using a new 2 way switch connect the black core of the new 3 core & cpc to terminal L1 remembering to put a piece of brown sleeving over the black core.
• At the new switch position, connect the grey core of the new 3 core & cpc to terminal L2 remembering to put a piece of brown sleeving over the grey core.
• At the new switch position, connect the brown of the new 3 core & cpc to the Common or terminal C.
• At the new switch position, connect the cpc in the back boxes earth terminal and or switch cover (if metallic) using earth sleeving to cover the bare core to the termination point(s).

The switch wires between two switches are often referred to as strappers.

NB Different ways of connecting the 3 cores between the two 2 way switches exist but its easiest if the same coloured strapper is connected to the same terminal in both switches.

NB CPCs are not shown in the interactive tools for clarity (plus drawing green/yellow striped lines is ricky in this software).