Switches are manufactured to provide a number of different options. They may be the size of a single unit or double depending on the number of switches provided.
There are two terms used for identifying the function of switches, which need to be understood.
This refers to the number of live outputs available on the switch.
One way light switch
One way switches are the simplest form of light switch used. They have one terminal for the live coming in, and one for the live going out.
Operation of the switch connects or disconnects the two.
Two way light switch
Two way switches have one terminal for the live going in and two for the live going out.
Operation of the switch makes connection to one or the other of the live out terminals. These are commonly used for two way lighting where the light can be switched on and off from two different light switches. A two way light switch can be used for one way lighting by simply leaving one of the two live out positions unused.
This refers to the number of switches housed in the unit.
Where switches have more than one gang, the terminals belonging to each are separated. This may be with a raised line in the moulding or, as shown here, by a physical gap between them.
Single gang light switch
The simplest light switch has one switch and is referred to as a single gang switch
Two gang light switch
Light switches housing two or more switches are available. The image shows a basic two gang light switch. Multiple gang switches are also available allowing several lights to be operated from the same point.
Identification of connection terminals
The terminal connections on the back of a switch will be marked for identification. ‘C’ or ‘Common’ is the live in terminal. ‘L1’ ‘L2’ are the live out terminals.