All You Need To Know On How To Change A Light Switch

Do you have an old-looking light switch? You may need to change it for various reasons; to add a stylish finishing touch to your home, have multiway control of light, or because it is just faulty, dirty or outdated. No matter what the case is, you can replace it without even the need for a qualified electrician!

Attaching a white platband to an electric wall switch

Wondering how to replace an old light switch with a new one? You may already know how to install outdoor lighting and change a plug socket, or maybe you have the best LED strip lights in your home, but what about this one? You’d be surprised to know how easy it is! Upgrading your switch is a great time to look into options of switch types for increased convenience, comfort, and efficiency. To help you with your DIY project, we’ve created this guide to talk you through the replacement process. Are you ready?

Selecting a new light switch

First of all, it might seem a bit silly, but make sure it’s not the light bulb you need to replace. Once you know for sure, you should consider the switch types that exist to choose one that meets your requirements

Types of light switch fittings

  1. Single-pole controls are the most common and the simplest. This button has just 2 positions—“on” and “off.” 
  2. Wall-mounted switch fittings, also known as ‘plate switches‘, can contain 1, 2, 3 or even more individual switches that let you control several different light fittings from one place. 
  3. You may also find versions that give you 2 and multi-way switching, which allow you to control lights using 2 or more different switches.
  4. Dimmers let you lower and raise the light level and may have a combined or separate on/off and dimming control. They’re wired similarly to a standard switch. Switches generally need a 16mm-deep mounting box. Some dimmers, though, may need deeper boxes. If you have limited space or want a button to be discreet, you may fit narrow architrave switches into your door frames. 
  5. Building regulations require that you can install only ceiling-mounted pull-cord switches in bathrooms and shower rooms.
close up to man's hand adjusting the volume in dimmer switcher

Safety first

When it comes to electrical safety, never take risks. Always follow the safety precautions listed below before you start any type of electrical work:

  1. Always switch off the mains power at the consumer unit/fuse box. Remember to remove the circuit fuse to isolate the circuit you plan to work on. To avoid any accidental replacement, put this in your pocket.
  2. You can also switch off the circuit breaker and lock it if you can.
  3. Put a note to the unit to advise those around you that you are working on the circuit.
  4. Use a socket tester or voltage meter for lighting circuits to check the circuit is dead.
  5. Be extra cautious when opening up multi-way switches. The lights they control must take power from the same circuit. If yours are incorrectly connected, there will be live wires at each switch position when one circuit is isolated.
  6. After you are done, check all finished work with a socket tester or a voltage tester for lighting circuits before using.
Long-haired woman turning off the light-switch at power control panel

Changing a three-way light switch

A three-way switch has 3 wires and possibly 4, depending on whether it has a ground wire. It allows you to control 1 appliance from 2 or more locations. Here’s all you should do.

Step 1: Take a picture of how each wire is connected to the switch

The switch may have either screw terminal connectors or push-in holes.

Step 2: Identify and mark each wire

A three-way switch needs 3 wires: a hot wire, a neutral wire, and a traveller. It will also have a green or bare copper grounding wire. The box may contain 1 or 2 cables or sets of wires. 

  1. Mark the wire connected to the coloured screw terminal (typically dark) as the “common” wire.
  2. Tag the 2 wires connected to the other 2 terminals as the “traveller” ones.
  3. Label the copper wire connected to the green terminal on the other side of the switch as the “grounding” one.

Step 3: Disconnect the wires from the old switch

  1. If wires are connected to screw terminals: turn each one with a screwdriver to loosen and slide the wire out with a pair of needle-nose pliers.
  2. If they are connected to push-in connection: the holes that they are pushed into will have a small slot beneath the hole. Insert a small turnscrew into that slot and push forward to release the wire.

Step 4: Connect the wires to the new switch

  1. Connect the common wire to the common terminal. You can identify it since it will be a different colour than the other two terminals.
  2. If the box contains 1 or 2 cables or sets of wires: attach the traveller wires to the remaining 2 terminals. You can either: A) use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw. Then, tighten the screw to secure the wire. B) push the wire into the hole on the same switch’s side as the coloured screw.
Man installing light switch with screwdriver

Step 5: Double-check that the switch is oriented correctly

You’ll see the word “top” written on the button indicating the side of the switch that should be vertically oriented toward the top.

Step 6: Push the wires back into the box

Push the wires back and then push the switch up against the box’s edge. Finally, tighten the mounting screws into place.

Step 7: Replace the switch plate and tighten the screws into place

Replace the plate of the switch but be careful not to over tighten it since it may crack under too much pressure.

Step 8: Turn the power back on

Go back to the breaker box and turn the power to the switch back on. Flip it on and off several times to ensure it’s working.

How to change a single-pole light switch

If the switch has On and Off on its body and it’s the only one that controls lights or receptacles, it’s a single-pole switch. To replace this kind, follow the steps below, but first, always keep safety in mind.

Safety first – Earthing light switches

The most familiar switch combination is a plastic faceplate and metal mounting box. In this case, the earth cores must be connected to the earthing terminal of the mounting box. However, if both your faceplate and mounting box are plastic and there’s no earthing terminal, you should run yellow/green sleeving over the bare cores and clamp their exposed ends with a connector. This way, if you decide to change to metal fittings in the future, you’ll be able to earth them quickly and safely.

Step 1: Test the switch

Make sure the power is off by flipping the switch on and off several times. 

A two gang, 120 volt single pole electrical switch box installed on a wooden stud

Step 2: Remove the switch plate cover

Turn the screws holding the faceplate in place counter-clockwise with a flat-head screwdriver to loosen them.

Step 3: Unscrew the switch’s mounting screws

Once you’ve removed the plate cover, use the flat-head screw to take out the screws mounting the switch to the wall. 

Step 4: Remove the switch

  1. Pull the switch away from the wall and expose the wiring, but leave the wires connected.
  2. With a multimeter or a non-contact voltage tester, make sure no power is going to the switch. If you are using a digital multimeter, ensure it’s in the lowest resistance range. Next, hold 1 probe against the grounding wire (green or bare), and touch the other one to each of the terminals to see if the switch has any voltage. If you’re using a non-contact voltage tester, turn it on and hold the probe’s tip near each of the terminals, one at a time.
  3. If you detect voltage or hot wires, stop until you can turn off the power to the switch.

Step 5: Pull out the switch

  1. Pull the switch far from the electrical box.
  2. Take note of how the switch is wired. The wires will be connected to it by either terminals or push-in type.
  3. Take a picture so you can wire the switch in the same way.

Step 6: Check the wires inside the wall box and identify each wire

Use a marker to label each wire so you can tell them apart. The box will contain 1 or 2 cables.

  1. If it has 2 cables, it means the switch is in the middle of the circuit. You’ll see a total of 6 wires: 2 black wires, 2 green or bare copper ones, and 2 neutral wires, which may be black, white, red, or any other colour than green. Mark the wire connected to the brass screw terminal as the “hot” wire. Mark the wire connected to the hole on the same side as the silver terminal as the “neutral” wire. Finally, mark the copper wire connected to the green terminal as the “grounding” one.
  2. If the box contains only 1 cable (or a single set of 3 wires), it means the switch is at the end of the circuit. You’ll see a black wire, a green or bare one, and a third wire, which may be white, black, red, or any colour other than green. Mark the wire connected to the hole on the same side as the brass terminal as the “hot” wire. Mark the wire connected to the spot on the same side as the silver terminal as the “neutral” wire. Finally, mark the wire connected to the green terminal as the “grounding” wire.
a man with a flashlight on his head hanging room wall light switch installation with a screwdriver,

Step 7: Disconnect the wires from the old switch

Disconnect your existing switch by removing the screws. Pull the attached wires out slightly. There are 3 types of cables that run to most switches: black ones that go to brass or black screws, green or copper ground wires attached to green or copper screws and neutral white wires. Unscrew all of them. If they are attached using push-in type, release them using a screwdriver.

Step 8: Attach the wires to the new switch

Attach the wires to the switch in the same configuration as you removed them. Ensure that the new wall plate fits and that the switch is oriented so that it’s downward in the off position. You should also check any wire connections and replace them if needed.

Step 9: Complete your project

  1. Screw the switch back into the box. 
  2. Flip the breaker box switch back on before replacing the wall plate to make sure everything works.
  3. Turn the breaker box, switch it off again and attach your plate. 
  4. Turn the breaker box back on, and you’re ready to use your advanced switch!
close up to female hand with french manicure going to turn off light switch

Changing a dimmer switch

A dimmer switch lets you control the brightness of a light fixture. Follow the same process as above to change it. Here are the basic steps:

  1. Mark each wire in the switch box as hot, neutral and grounding.
  2. Disconnect the wires from the old device.
  3. Connect the wires to the new switch using a wire stripper. Most dimmer switches come with cables that are already attached, 2 black lead wires and 1 green grounding wire.
  4. Double-check that the switch is oriented correctly.
  5. Push the wires back into the box, push the switch up against the box’s edge and tighten the mounting screws into place.
  6. Replace your switch plate and tighten the screws into place.
  7. Go back to the breaker box and turn the power to the light switch back on. You’re done!

How to convert to two-way switching from one-way control

You should do 3 critical things if you want to change from one-way control to two-way switching. 

  1. Replace your original switch with a 2-way fitting
  2. Install the new two-way switch at the second control point. 
  3. Link the two with 1mm2 three-core-and-earth wire. Next, run the cable between the two switch positions and install a metal mounting box at the current switch position.
Installation of the wall outlet in the mounting box

Are you a confident do-it-yourselfer? Most professionals agree that changing your light switch is a simple and safe task for anyone. Keep in mind that, as with all projects involving electricity, it’s crucial to exercise caution. Now that you have all the information you need, go ahead and get the job done safely and effectively. Upgrade your home and make sure you’re never left in the dark again!

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