When a light needs to be switched on or off from two separate positions which is usually the case 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 and have a Twin and Earth cable connecting one of the switches 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 on its own to the common on the light switch and the black of the 3-core along with the brown of the Twin and Earth go together 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. The grey and black conductors are referred to as the ‘strappers’
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 terminals on the back-boxes and switch plates as necessary.
If needed additional switching positions can be added through the use of intermediate lighting switches which are placed in between the two-way switches and work by crossing over the strappers when switched. Note all non brown conductors need to be sleeved brown.