I'm taking a basic electronics course and we were working with bathroom fan timer circuits, I heard in the course you could adjust the length of the bathroom fan timer by changing the value of the potentiometer in the circuit. This was interesting to me because I wanted to change the length of the fan timer in our house.

I opened up the fan and found the potentiometer, tried to rotate it but it didn't want to move. Before I went further I poked around with my multimeter to see if capacitors were charged so I didn't hurt myself. With the multimeter I accidentally connected what I believe to be the mains wires, and blew a fuse in our house.

All is well and good, I have learned my lesson (I should have turned off the power at the breaker, I had believed that since the light was off no power would be in the circuit), but now the bathroom fan makes a disgusting whirring sound when it's on. Is there a simple solution to this or do I need to suck it up and tell our landlord I broke the fan and get someone more qualified than me to fix it?

Note: Yes I shouldn't have been messing around in the circuit, you are correct, I am not qualified, that was a mistake. My question here is about simple things I can do safely at the moment, or if it's sufficiently unclear what the right thing to do is so I should get someone more qualified.

Details that may be useful: I live in the UK

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  • UK power uses 220 volts, so you get more bang when you make a short, it also hurts much more than NA 120 volts. You probably blew the electronics in the fan from the short. Most newer stuff is not built for repair parts, mainly replacement.
    – crip659
    Nov 27, 2022 at 11:26
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    Even if you were qualified, you're not supposed to be working in a rental unit unless hired by the landlord. Finish your class before trying to "fix" anything else. :-)
    – JACK
    Nov 27, 2022 at 14:14
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    "I had believed that since the light was off no power would be in the circuit" This is unlikely to be true in the UK. tbh, whatever course you're on, they should have told you this, day one. The power runs in the ceiling, with loop to the switch itself, which is also permanently live on one side.
    – Tetsujin
    Nov 27, 2022 at 15:02

1 Answer 1


No lecture here, as you seemed to have learned your lesson. The "right" thing to do is call the apartment's maintenance department (or person). Tell them your bathroom fan isn't working. They will send someone to take a look at it and more than likely order a new one. As someone with trade experience, I'd know those marks were the result of a short. I'd also be able to tell the unit was recently opened and worked-on (either by noticing drywall bits, paint line discrepancies, fresh lines in the dust in the housing, lack of dust on the wires, etc.). The maintenance person may not care and just have it replaced or they may go back and say it was the result of someone working on it, which places fault on you since it's a rental. Only the two little characters on your shoulders will tell you whether to admit it or pass it off as not knowing what happened...

  • Many thanks for the answer, I've contacted our landlord and explained the situation. Will likely need to cough up some cash but at least the guy that comes will get a laugh when I explain the situation and might be able to teach me some stuff about the circuit.
    – Jack
    Nov 27, 2022 at 20:37
  • @Jack At least this time it was only the fan. Just got lucky it did not toss you out of a 30th floor window. Always double check no power to what you are working on, is it the right breaker you turned off.
    – crip659
    Nov 27, 2022 at 22:16

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