Bathroom fan won’t turn off? The most likely cause is a faulty switch. The switch might have a broken switch mechanism, loose wires, damaged wires or simply wired incorrectly.
This post will go into the four different reasons why your bathroom fan won’t turn off.
While a bathroom fan not turning off is inconvenient, it’s almost always caused by a problem originating at the switch.
The simplest solution for the electrician is to install a new switch.
Bathroom Fan Won’t Turn Off? – Reason #1
Broken Switch Mechanism
The first potential reason why the bathroom fan won’t turn off is a broken switch mechanism.
The switch mechanism is the part of the switch which opens and closes the circuit (turns on and off the bathroom fan).
As discussed in this post, the switch mechanism can wear down over time.
A switch mechanism typically contains small plastic parts, springs, and the switch contact. When a part inside the switch mechanism breaks or moves out of place, such as the spring for example, it can lead to the switch mechanism no longer working as intended.
This can result in the bathroom fan staying on because the switch mechanism isn’t working to turn it off.
To work out if this is the cause of the problem you should inspect your light switch.
How To Inspect Your Light Switch
Check how the switch feels when it is pressed.
- Does the switch feel more difficult to press than other switches in the house?
- Does the switch feel sloppy and loose?
- Does the switch look uneven or stick out?
- Does the switch feel jammed?
If the switch feels weird compared to other switches in the house then it could be the cause of the problem. Luckily, the solution is relatively simple and cheap – replace the switch.
Bathroom Fan Won’t Turn Off? – Reason #2
Damaged Wires
Damaged wires can cause the wire going to the fan to come in contact with a live feed. This can mean that the bathroom fan won’t turn off. This happens because the insulation has become exposed for some reason allowing contact between wires.
Wires can be damaged for many reasons including rodent damage or sharp objects in the ceiling cavity. Polystyrene insulation can damage cables by degrading the insulation exposing the wires.
If you have polystyrene insulation in your house and find that your bathroom fan won’t turn off, then it might be a good idea to talk with an electrician to ensure that your wiring complies with AS/NZS:3000 wiring rules.
Bathroom Fan Won’t Turn Off? – Reason #3
Loose Wires Touching Live Feed
When connecting wires (terminating wires) at the light switch, they need to have a certain tightness. The wires shouldn’t be screwed too loose, or too tight.
If wires are too loose, they may eventually come out of their terminals and come into contact with the live feed located nearby on the light switch.
If this happened it would cause the bathroom fan to stay on and become unresponsive to the switch.
If you think this might have happened when the bathroom fan was originally installed then the next reason might be relevant as well.
Bathroom Fan Won’t Turn Off? – Reason #4
Incorrectly Wired Switch
Dodgy wiring could be why the bathroom fan won’t turn off.
It’s possible that the switch was incorrectly wired when it was installed.
Here is how you might be able to tell:
- Turn on and off other lights in the house and see if this causes the bathroom fan to turn off.
- If the bathroom fan turns off when an unrelated light turns off, then it is possible they have a connected power feed.
This is a screw-up by whoever wired the switch.
I see things like this happening all the time. It is surprisingly common.
If you suspect that the switch has been incorrectly wired then it is best to get in contact with a registered electrician to resolve the issue. Incorrect wiring is dangerous and can lead to electric shocks or fires.
Conclusion
Bathroom fan won’t turn off? The most likely cause is a faulty light switch caused by a broken switch mechanism or loose wires. You can take a photo of the light switch and visit your electrical retailer to get a replacement before calling the electrician.
The fault might also be caused by incorrect wiring involving the bathroom fan.
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