How to Wire a Light Switch

While it is the work of electricians to wire a house and electrical outlets, a homeowner can still do some simple installations like switch wiring.

If you have ever had a faulty outlet such as a light switch or socket but can’t get an electrician to replace it immediately, you will know why a basic knowledge of electrical wiring is good.

In this article, I will guide you on how to wire a light switch, and the tools required.

Wiring a light switch is one of the easiest things in electrical installation, especially a single pole light switch. But for non-electrical workers, it always seems to be hard.

Below is a step-by-step guide on how to wire a light switch in your domestic or residential home.

Tools required for light switch wiring.

  • Screwdriver
  • Plier
  • Wire stripper
  • Plumb
  • Electrical tape
  • Voltage tester and a new light switch.

Wire colours and where to use them.

  • Black wire: This is a load or hot wire.
  • White wire: Neutral
  • Red wire: Used in 3 or 4-way switch wiring to connect switches together to control the lights.
  • Green or bare copper: Earth or ground wire.

Note: Before you work on the electrical system, always turn OFF the control switch or the circuit breaker that controls the branch circuit, and also wear your electrician glove.

A single pole light switch wiring diagram

Wiring a single pole or one-way light switch is easy, it requires 3 wires. Two black or hot wires, and the earth cable.

Just draw the cables from the distribution board (DB) or junction-box, connect the black wire to the dimmer or switch, and then to the bulb. Draw the earth or grounding wire straight from the DB to the switch and then to the bulb. Also draw the neutral from the power source to the bulb to complete the circuit.

The reason the black or hot wire was first connected to the switch is to control (open and close) the circuit.

After the connection, tighten the switch on a receptacle or switch box on the wall.

How to install a 2 way switch wiring

A 2-way switch, also called staircase switches, allows you to control a single bulb from two different locations. It is useful in staircase lighting, and hallway as you can switch ON the light before climbing upstairs and also OFF the light with the second dimmer switch.

The 2 way switch has three terminals: COM, L1, and L2.

Methods of wiring a 2 way outlets

There are two methods of wiring a 2 way switch, the standard or 3 wire control and the old or 2 wire system.

Standard 2 way switch wiring (3 wire controls)

This wiring method requires two (2-way switches) and three-wire controls such as Romex. It uses the new standard wire recommended by National Electrical Code.

Below is the wiring diagram for a standard 2-way outlet.

From the schematic diagram, you can see that we connected the live wire to the L1 of the two switches, we also connected the L1 to the respective COM before linking the two COMs together.

We equally connected the L2 terminals of the two outlets to the bulb, and the neutral of the bulb, to that of supply.

You can close and open the circuit from any of the toggle-switches above.

2nd method: 2 way switch wiring (2 wire control)

Although this method saves wire, it is no longer in use with the emergence of the new cable colours.

If you still have the old wire in your home, you can still use the 2 wire controls.

Below is the wiring diagram.

2 way

From the wiring diagram, you can see that we connected the live wire from the DB to the COM of the first dimmer, we then ran two traveling wires connecting the L1 to L1, and L2 to L2 of the two dimmers.

And finally connected the second COM to the bulb, and also the neutral wire from the DB.

Whenever you toggle any of the two switches, it lights on or opens the circuit.

Frequently Asked Questions

Does it matter which wire goes where on a light switch?

No, it does not matter provided it is a single-pole switch with two terminals. The light switch doesn’t have neutral terminals, it’s all hot wires from the supply and then to the bulb.

What does L1 and L2 mean on a light switch?

The L1 and L2 on light switch means line 1 and line 2, while COM is common.