Lighting Circuits - Switch Arrangements

The three types of switch can be arranged in groups.

One gang

One way switch Two way switch Intermediate switch

'Gang' refers to the number of switches on a single mounting plate.

The diagrams here are all one gang, as there is one switch on each plate. The switches themselves are one way, two way and intermediate.

Two gang

Two gang, two way switch, triangle terminal arrangement A Two gang, two way switch, triangle terminal arrangement B Two gang, two way switch with inline terminals

Where two switches are mounted on the same plate, this is a two gang switch. There is no electrical connection between the two switches.

The examples here show three possible arrangements. All of these are two way switches.

First, switches with terminals in a triangle arrangement. The left COM, L1 and L2 are for one switch, and the right COM, L1 and L2 are for the other switch.

The second example is the same, except that one switch is the other way up. A common mistake with these is to assume the top terminals are for one switch - this is wrong. The top COM and the bottom L1 L2 are one switch. Here, the switches are shown with a space between them. In reality, the back of the switches is usually one moulded piece.

The third diagram shows all of the terminals in a line. This is common with dimmer switches.

Three gang

Three switches on one plate. As with the two gang units, various combinations are possible.

Three gang, two way switch, triangle terminal arrangement A Three gang, two way switch, triangle terminal arrangement B

The second arrangement is the most common. The centre switch is inverted compared to the other two.

Again, each 'triangle' of terminals is one switch, and are shown here with a small space between each switch. Real switches usually have a single lump of moulded plastic on the back.

Four gang and more

Four and more switches on a single plate are available, although the mounting plates will be larger.

Two gang and above will normally all be two way switches. As seen previously, a two way switch can be used as a one way, and the cost difference is minimal.

Finding intermediate switches in two gang or more is difficult. Intermediates with other types on the same plate is almost impossible.

What about the front?

Switches are available in a large number of types, such as white plastic, chrome, brass, extra large, toggle, black anodised, coloured plastic or shaped like animals. Whatever the appearance, the electrical connections to the switch are the same.

Metal switches will have an earth connection. This will be a separate terminal, and will be attached to the metal plate.