Light Wiring Diagrams

Single gang 1 way light switch

There are two terminals in a one way light switch. When the switch is on, both terminals are connected together.

Typically, these terminals will be marked COM and L1 (sometimes L1 and L2). Although, technically, it doesn’t matter which way round you connect the wires, it is best to stick to convention and connect the permanemt live (from the supply) to COM and the switched live (to the lamp) to L1.

This is the most common type of switch, and is used where a light is controlled from a single switch (although you will often see a two way switch used, with one terminal left unused).

single gang switch face

single gang switch face

Single gang one way light switch

Single gang one way light switch

Switch mechanism

One way light switch mechanism

One way light switch mechanism

This is fairly obvious, but when the switch is ‘on’ the COM and L1 terminals are connected together. When ‘off’ they are not.


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Single gang 2 way light switch

A two way light switch has three terminals and is quite like a sigle way switch but now the ‘off’ position can be utilised also.

Some brands of switch may have slightly different labeling on the terminals (such as C L1 L2 or even L1 L2 and L3).

This type of switch is used where two switches control the same light, such as at the top and bottom of a stairway. You can use it as a one way switch, by using the COM and L1 terminals only.

single gang switch face

single gang switch face

Single gang two way light switch

Single gang two way light switch

Switch mechanism

Two way light switch mechanism

Two way light switch mechanism

In position 1 (when the switch is down or ‘on’), COM and L1 are connected together (just like the one way switch). In position 2 (when the switch is up or ‘off’), COM and L2 are connected together.

There is never a connection betweeen L1 and L2.


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2 gang 1 way light switch

You don’t see these as much now days as many manufactures only make 2 gang 2 way light switches that serve the same purpose (you just don’t use the third L2 terminal on each gang), however I thought we would include it just in case you come across one!

Basically, this is just two single way switches on one face plate

Double gang swith face plate

Double gang switch face plate

Double gang one way light switch

Fig 2: Double gang one way light switch

Switch mechanism

One way light switch mechanism

One way light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are two) work like this: when the switch is ‘on’ the COM and L1 terminals are connected together. When ‘off’ the COM is connected to nothing.

There are no connections between the two gangs in Fig 2. Each gang is a single discreet switch.


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2 gang 2 way light switch

This switch arrangement is basically two two way switches on a single face plate.

Some brands of light switch may have slightly different labeling on the terminals (such as C L1 L2 or even L1 L2 and L3).

Double gang swith face plate

Double gang switch face plate

Double gang two way light switch

Fig 2: Double gang two way light switch

Switch mechanism

Two way light switch mechanism

Fig 3: Two way light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are two) work like this (Fig 3): In position 1 (when the switch is down or ‘on’), COM and L1 are connected together (just like the one way switch). In position 2 (when the switch is up or ‘off’), COM and L2 are connected together.

There are no connections between the two gangs in Fig 2. Each gang is a single discreet switch.

Just to be different:)

The terminals on your switch may be a little different to those shown above but rest assured they function just as described above but the terminal pins are in different positions. You may see the following:

double gang two way light switch terminal variation 1

double gang two way light switch terminal variation 1

double gang two way light switch 3

double gang two way light switch terminal variation 2


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3 gang 1 way light switch

This format of light switch has three discreet switches on a single face plate. Basically this is three Single gang 1 way switches on a single face plate.

The only place you would use such a beast is if you had three lights (or sets of lights) in a single room each controlled by one of the single switches. This arrangement is not common, you are most likely to find a 3 gang 2 way switch used (this will do the same job but you will have spare L2 terminals on each gang that you would not need to use).

Triple gang switch face

Triple gang switch face

Triple gang one way light switch

Fig 2: Triple gang one way light switch

Switch mechanism

One way light switch mechanism

One way light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are three) work like this: when the switch is ‘on’ the COM and L1 terminals are connected together. When ‘off’ the COM is connected to nothing.

There are no connections between the two gangs in Fig 2. Each gang is a single discreet switch.


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3 gang 2 way light switch

This format of light switch has three discreet switches on a single face plate. Basically this is three Single gang 2 way switches on a single face plate.

Triple gang switch face

Triple gang switch face

Triple gang 2 way light switch

Fig 2: Triple gang 2 way light switch

Switch mechanism

Two way light switch mechanism

Fig 3: Two way light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are three) work like this (Fig 3): In position 1 (when the switch is down or ‘on’), COM and L1 are connected together (just like the one way switch). In position 2 (when the switch is up or ‘off’), COM and L2 are connected together.

There are no connections between the three gangs in Fig 2. Each gang is a single discreet switch.


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1 gang intermediate light switch

The intermediate light switch is used where three or more switches control one light and used in conjunction with two two way light switches to achieve this

single gang switch face

single gang switch face

Single gang intermediate light switch

Single gang intermediate light switch

Light switch mechanism

Intermediate light switch mechanism

Intermediate light switch mechanism

There are four terminals, usually L1, L1 and L2, L2. In one position, L1 and L2 are connected in pairs. In the other position, alternate pairs are connected.


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2 gang intermediate light switch

The intermediate light switch is used where three or more switches control one light and used in conjunction with two two way light switches to achieve this. It is effectively two single gang intermediate switches on one face plate.

Double gang swith face plate

Double gang switch face plate

Double gang intermediate light switch

Fig 2: Double gang intermediate light switch

Light switch mechanism

Intermediate light switch mechanism

Fig 3: Intermediate light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are two) work like this (Fig 3): There are four terminals, usually L1, L1 and L2, L2. In one position, L1 and L2 are connected in pairs. In the other position, alternate pairs are connected.


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3 gang intermediate light switch

The 3 gang intermediate light switch is used where three or more switches control one light and used in conjunction with two two way light switches to achieve this. It is effectively three single gang intermediate switches on one face plate.

Triple gang switch face

Triple gang switch face

Triple gang intermediate light switch

Fig 2: Triple gang intermediate light switch

Switch mechanism

Intermediate light switch mechanism

Fig 3: Intermediate light switch mechanism

Each of the gangs (or switches) above in Fig 2 (of which there are three) work like this (Fig 3): There are four terminals, usually L1, L1 and L2, L2. In one position, L1 and L2 are connected in pairs. In the other position, alternate pairs are connected.


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