Light Switch Broken? Here’s Why

We often take light switches for granted. They’re seemingly simple objects that literally get to say, “let there be light!” for every moment of their life. But when your light switch is broken, you’re left in the dark – which is no fun. This could mean a lot of different things, so it’s important to know what you’re looking for when troubleshooting a busted light switch. Luckily, DreamyHome is here with all of the advice you could ever possibly need.

The most common reasons a light switch would be broken are a broken switch, bad fuse, loose wiring, electrical faults (hot switch), or a faulty circuit cable.

Let’s break that down a bit more so you know if there’s a reason for concern or just simple annoyance.

Troubleshooting a Light Switch That’s Broken

We’re going to delve into the fixes in a moment, but first, let’s figure out what’s wrong. There are five main things to look for, some of which may point to more serious issues in your home’s wiring. Let’s start with the less concerning ones, and move on to the serious issues in time.

#1 Broken Switch

This is the most likely cause of a light switch not working. Just like all parts of your home (and everything else in life), light switches have a lifespan – they don’t live forever. If you’re noticing that your switch won’t turn on or off, regardless of whether you switch it, it’s likely time for a replacement. You may also notice that the switch won’t stay in one fixed position, which means the same thing.

#2 Fuses

Burnt fuses and tripped breakers are rather common, especially in older homes. Whenever you have issues with electronics, it’s best that you take a look at your breaker box as one of the first stops. You can replace burnt fuses and flip the breaker back, but if it happens regularly, that’s a sign of something else.

If you’re repeatedly replacing fuses or flipping the breaker, you may need an electrician to take a look at your home’s wiring.

#3 Bad Wiring

This is where things start to get hairy. If your lights are flickering or fainter than normal (and you’ve already replaced the light bulb), that is a sign of bad or loose wiring. You have two options here – turn off power and open that bad boy up (which we’ll get to in a moment), or call a pro for help.

#4 Hot Switch

This doesn’t always mean that your light switch is literally hot. It means that you are hearing a buzzing or humming sound coming from the switch, not the bulb. If the switch is hot, that’s an obvious sign of an issue.

If you notice either of these issues, turn off power at the breaker to your switch immediately and call an electrician. This is a serious fire hazard and could be a very major problem.

#5 Circuit Cable

You can use a multimeter to check this out if you have one. Otherwise, this is a job for an electrician. If you’ve tested everything else and done all of the fixes we mention below, you’ll want a pro to take a look – this isn’t for the layman to fix.

The Fix(es)

No matter the problem, you’re going to need a few things to address any of these issues. You’re going to want a flathead or Phillips head screwdriver (depending on the screws in your switch), a multimeter, and needlenose pliers.

No matter what it is that you’re trying to fix, remember the golden rule of electrical work – don’t work with live circuits unless you enjoy being electrocuted.

Additionally, cap all wires that you’re working with and mark anything you’re using with electrical tape. It never hurts to be safe and plan ahead, it often hurts not to.

Let’s start with the obvious fix – replacing the light switch.

Fully Replacing Your Light Switch

This is surprisingly easy, so I recommend trying this first. Go buy a new switch. Now, you need to:

Replacing Modern Switches

  1. Turn off power to the switch.
  2. Remove the cap by taking out the screws holding it in place.
  3. Insert your screwdriver (flathead works best here) under each wire, and gently pry upwards. It should pop easily out of place. Pull gently on the wire if you’re finding resistance, but don’t yank.
    1. The white wire should connect to a silver screw, or will go behind the switch mechanism to the same side as the silver screw.
    2. The black (sometimes red) wire is the “hot” wire. It goes to the brass screw.
    3. The green or bare copper wire is the ground wire. This goes to the green screw terminal, or straight to the electrical box, depending on your home.
  4. Carefully replace the new wires where the old ones came from. Don’t mix them up. Replace the cover and test your new switch.

If it’s a single-pole switch (it just says on/off) do this:

  1. Do steps 1 and 2 from above. Remove the switch mechanism (the whole metal piece that wires attach to) with the wires still attached.
  2. If there’s a white wire with black electrical tape, this is the “black” wire from above – it’s not a neutral wire, in other words.
  3. Since your power is off (right?!) this is an easier process. Simply compare your new switch and old, popping the wires into place one by one, rather than all at once.
    1. You’re colour-matching here. Green goes to copper screw, silver screw gets the white wire, the brass screw gets the black (or white wire, taped black) wire.
  4. Replace the cover and test your new switch.

Three-Way Switches

This is a switch with 3 or 4 wires. They won’t say “on/off,” and will work in two places (like the top and bottom of stairs). To replace it, do the following:

  1. Do steps 1-3 above, ensuring the circuit is dead with a multimeter.
  2. The big difference here is that two wires will attach to the brass screw, and a new wire (dark coloured, not green) will go to the terminal that’s usually at the bottom.
    1. Mark the extra wire with tape, and the wire on the same side with a different piece of tape. You don’t want to get them confused.
  3. Remove all wires from the switch.
  4. Attach the tagged wires to their corresponding terminals/screws.
    1. If the old switch has a green ground wire, it goes to the new switch’s green terminal screw.
  5. Replace and test.

Four Way Switches

These are the kind that are on switch plates between 2 or more other switches. To replace one, do this:

  1. Do steps 1-3 above, looking for the fourth (or fifth) terminal screw. These are usually green, meaning they’re the ground wire.
  2. Mark each spot with tape before disconnecting the wires from the old switch so you can tell where to put the new ones.
  3. Attach the wires to their corresponding terminals. You can do this one at a time to make it easier.
  4. The green wire goes to the ground terminal or straight to the electrical box.
  5. Replace and test.

Replacing a Dimmer Switch

Generally, dimmer switches will be on single-pole or three-way switches. This is the same process, with a slight change. Remember, dimmers don’t work on fluorescent fixtures or low-voltage lighting unless specifically marketed as such.

Most dimmer switches can handle up to 600 watts of power. Be sure to check that your light fixture’s bulbs altogether don’t go above your dimmer’s power rating to avoid overloading the dimmer.

Now, do the following:

  1. Do steps 1-3 (or 4) of your respective light switch’s method. Go all the way to removing the wires from the old switch.
    1. Dimmers are usually attached to the house wiring rather than with screw terminals.
  2. Use connectors (aka wire nuts) to attach the black wires in the dimmer to the coloured wires of the terminal on the old switch.
    1. Twist the (naked) wires together and then screw the wire nut on.
  3. Replace the cover. Don’t force the dimmer in, you’ll likely have to finagle a good resting place for it. Don’t be afraid of organizing your wires a bit to make this easier.
  4. Push the control knob (if you have one) onto the bit protruding from the switch.
  5. Test.

When to Call a Professional

If you’re noticing that your breaker is going off regularly or you’re replacing fuses often, you’ll likely want to call a professional for help. You can always test your fuse box, circuit cable, and wiring with a multimeter to see if it’s a problem, but that’s as far as you should go unless you’re a professional electrician. And you aren’t, otherwise you wouldn’t be here, would you?

Issues stemming from poor wiring, hot circuits, or issues with the breaker are all complicated and can at times be serious issues. Let the professionals do their job and make your life easier. But by all means, try replacing the switch first.

Final Thoughts

Light switches are complicated. There’s wiring going all throughout your house, so it’s important to be aware of possible issues. Buzzing light switches (not light bulbs) are a sign of serious problems, as is a regularly tripping breaker. But if your switch simply doesn’t work or won’t stay in a fixed position, replacing it is often the fix it needs.

Follow the steps above, remember to turn off the power before working with wiring, and be safe, okay? We like having you visit our site, and there’s no sense in getting electrocuted because you couldn’t be bothered to call an electrician for help.

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About the Author Harry Thompson

Involved in home renovations throughout his life, Harry is an expert in everything to do with home and garden DIY. In his spare time, he enjoys cooking and tending to his garden.