Light Switch Wiring Guide: Both Single Pole, Two-Way & Dimmer.

Welcome to In this article, you will learn how to wire a light switch. Both a single pole light switch, two-way, and dimmer switches.

Though it is the work of a licensed electrician to wire a house and electrical box, you as a homeowner can still do some simple installations such as light switch wiring.

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

Below is a step-by-step guide to wiring a light switch in your domestic or residential homes.

Tools required to wire the switch box.

  • Screwdriver
  • Pliers
  • Wire stripper
  • Plumb
  • Electrical tape
  • Voltage tester and a new toggle-switch.

Wire colours and where to use them.

  • Black copper 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 wire 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.

Wiring a Single Pole or one way light control

Wiring a single pole light switch is easy, it requires 3 insulated wires. Two hot wires, and a ground wire.


  • Connect the black wire from the junction box to the dimmer or switch box, and then to the smart bulb.
  • Draw the earth or ground wire straight from the distribution board (DB) to the switch and then to the incandescent.
  • Also draw the neutral wire from the power source to the light fixture to complete the circuit.

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

After the connection, tighten the switch on the electrical box.

How to wire a 2-way smart switch

A 2-way light switch, also called staircase switches, allows you to control a light bulb from two different locations.

It is useful in staircase lighting and hallways as you can power ON the light before climbing upstairs and also OFF the light fixture when you climb up.

The two-way switches have three screw terminals: COM, L1, and L2.

Methods of wiring 2-way switches

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

The standard 3 wire control method

This wiring method requires two (2-way switches) and three-wire controls such as Romex. It uses a new standard wire recommended by the 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 light fixture or 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: Two-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 diagram, you can see that we connected the live wire from the DB to the COM of the first dimmer, we then ran two traveler 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.

How to install a dimmer switch

How to install a dimmer switch

Dimmer installation is quite easy, it is like single-pole wiring. Dimmers usually come with three short wires, two blacks, and one earth wire.

Installation procedures

Before any installation, check the power rating of the dimmer you buy. Most of them can handle up to 600 watts.

Check the wattage of your bulbs and make sure you did not overload the dimmer.

Note: Dimmer switches don’t work on most fluorescent and LED bulbs. These lights require low-voltage dimmers.

Here are the steps to follow.

  • Turn OFF the power from your electrical panel
  • Unscrew the switch plate and also check the circuit with voltage tester to make sure it is dead.
  • Lose the switch from the electrical box and pull it out.
  • Disconnect the old wires from the switch and connect the dimmer.
  • Use the connectors that come with the fixtures to connect the wires, respectively.

Frequently Asked Questions

Does it matter which wire goes where on a smart 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 is the meaning of L1 and L2 on a light switch?

L1 and L2 means line 1 and line 2, while COM is common.

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