How to wire a light switch

How to wire up light switches

If you find yourself asking how to wire a light switch then the simple answer is don’t, the amount of times electricians find incorrectly and sometimes dangerously connected light switches is far too often.

A common issue is with metal light switches where the yellow core of a 3 core cable at a 2 way light switch has been connected to the earth terminal of the light switch. When the two way switches are in a certain position the yellow core of the cable will become live.

As many electricians discover on a daily basis DIY electrical works are generally dangerous, non-compliant and normally ends up costing a lot more in the long run due to the costs involved to correct and make safe the DIY works.

Another common issue electricians are finding with DIY fitted light switches is where the earth core of the cable is being used as a live conductor, which of course is non-compliant and dangerous.

Types of Light Switches

There are many types of light switches, 1 way, 2 way and intermediate, then is the number of switches on a switch plate, 1 gang, 2 gang, 3 gang and so on, then there are many types of dimmer switches, leading edge, trailing edge, LED etc. There is also varying IP rated light switches.

Each type of light switch connection is different, the wiring diagram for a 1 way light switch is different to the wiring diagram for a 2 way light switch. It is important to ensure the correct light switch is selected for its intended use.

How to wire up a light switch
1 Gang 1 Way Switch

1 Gang 1 Way Light Switch

A 1 gang 1 way light switch can be used to switch on and off a light fitting, if the same light fitting needs to be switched from two different positions i.e. top of stairs and bottom of stairs then a 1 gang 2 way light switch is required, one at the bottom of the stairs and another at the top of the stairs.

2 Way Light Switch Connections
1 Gang 2 Way Switch

1 Gang 2 Way Light Switch

A 1 gang 2 way light switch is used to switch on and off a light fitting from two different switches, for example a large room may have two entrances where you want to be able to switch the lights on and off from.

Intermediate Switch Wiring Diagram
1G Intermediate Switch

Intermediate Light Switch

An intermediate light switch is required when you wish to turn on and off a light fitting from more than two different switches, for example a large room may have three entrances where you want to be able to switch the lights on and off from each entrance.

Incorrectly Connected Light Switch

A light switch which has been connected incorrectly can cause a number of issues such as;

  • Light wont turn off
  • Light wont turn on
  • Light flickers when wrongly connected to two 2 way light switches
  • Metal light switch becomes live / trips when the yellow strapper core has been connected to the earth terminal

Dimmer Light Switches

When selecting a dimmer switch it is important to ensure the correct dimmer switch is selected matching the rating and type of lamps it is to dim. Dimmer switches have a maximum load they can dim, for example a standard incandescent 100 watt dimmer switch can only dim up to a maximum of a 100 watt incandescent load. If you exceed this maximum load it can cause the dimmer switch module to melt due to it being overloaded.

LED dimmer switches are available in many types and ratings, for an LED dimmer switch it is best to contact the manufacture of the LED lamps who can advise on the best suited LED dimmer switch.

How to Wire a Light Switch

Summery, how to connect or wire up a light switch = Contact a competent Electrician to do it!