How to connect a 2-way lighting circuit…
When a single light needs to be switched on and off from two positions such as on stairs or landings a two-way lighting switch arrangement can be used. The most common and easiest way of doing this is to link both of the light switches together using a 3-core and CPC – PVC cable along with a Twin and Earth cable as a main and switch wire from one of the switches up to the ceiling rose of the light to be switched.
The switches used in this instance are two-way switches and have three connections which are called common, L1 and L2. The Twin and Earth cable connects at the ceiling rose the same way as previously with the brown in the central ‘loop’ connection and the blue in the two terminal connection along with the brown line conductor of the lamp holder. Don’t forget the brown sleeving on this blue conductor as before.
At the first switch we have the brown, blue and CPC of the Twin and Earth and along with the brown, black, grey and CPC of the 3-core cable. The brown of the 3-core connects to the common on the light switch and the black of the 3-core along with the brown of the Twin and Earth go tegether into terminal L1 of the switch. This leaves the grey of the 3-core and blue of the Twin and Earth and these go together into the L2 connection of the switch.
On the second switch the 3-core connects to the same terminals as the first switch. Brown, common. Black, L1 and grey, L2. All CPCs should be connected to termianls on the backboxes and switch plates as necessary.
See the image below for a working example of 2-way switching on a lighting circuit…
Note: If needed any additional switching positions can be added through the use of an intermediate lighting switch which are placed in between the two-way switches