If the extractor fan and the light have both stopped, that is actually useful information. It means the fault is almost certainly upstream of both of them rather than in either one — they are fed from the same circuit, usually through the same switch or the same fused spur.
Two separate things failing on the same day is rare. One thing feeding both failing is common.
The five usual causes
1. The fuse in the fan’s isolator has blown. Most bathroom fans are fed through a fused connection unit or a three-pole isolator switch, often just outside the bathroom door or in the loft above. There is a small fuse in it, typically 3A. If that goes, it takes the fan and — depending on how it was wired — the light with it. This is the single most common cause and the cheapest fix.
2. An RCD has tripped at the fuse board. Go and look at the board. If a switch has flicked to the off or middle position, that is your answer. Bathrooms are damp, and moisture getting where it should not is a classic RCD trip. Worth knowing: if you reset it and it trips straight back, stop — something is genuinely faulty and it needs finding, not resetting repeatedly.
3. The light switch or pull cord has failed. Pull-cord switches in bathrooms live a hard life — humidity, and being yanked several times a day. The mechanism wears out and the contacts fail. If the fan is wired to switch with the light, the switch failing takes both.
4. The fan itself has seized and taken the fuse with it. Extractor fans are cheap motors in a wet room. When the bearings go the motor draws more current, and it blows the fuse on the way out. If the fuse blows again immediately after replacing it, the fan is the problem, not the fuse.
5. A cable or connection has failed in the loft. Less common, but it happens — particularly where a fan was retrofitted and the connection was made with a choc-block sitting loose in the insulation rather than in a proper enclosure. Loft temperature swings and rodents both take their toll.
What you can safely check yourself
Two things, and no more:
- Look at the fuse board. Has anything tripped? Reset it once. If it holds, note what you were doing when it went. If it trips again immediately, leave it off and call someone.
- Check whether other lights on the same circuit are out. If the landing light has gone too, the fault is further back than the bathroom, which is worth telling the electrician.
That is genuinely where it stops. A bathroom is a “special location” under BS 7671, and electrical work in one is notifiable under Part P of the Building Regulations. It has to be carried out by a competent person and certified. Changing a fan or a pull cord yourself in a bathroom is not a legal DIY job, regardless of what a video suggests.
When it needs looking at urgently
Turn the circuit off at the board and get it seen the same day if there is:
- A burning or fishy smell from the switch, fan or board
- Scorching or discolouration around an accessory
- Buzzing or crackling from the switch or the fuse board
- An RCD that trips again immediately every time you reset it
Those are not “book it in next week” symptoms.
How it usually gets fixed
The job is diagnosis first. An electrician should be establishing why rather than replacing parts until it works — that is the difference between a repair and an expensive guess.
In practice: test at the isolator to see whether supply is reaching it, check the fuse, test the switch, then the fan itself. Most of these faults are found in well under an hour.
Common outcomes:
- Blown fuse in the isolator — replaced, and the reason it blew established.
- Failed pull cord or switch — replaced with a proper bathroom-rated accessory.
- Seized fan — replaced, usually with an overrun timer model if the room needs it.
- RCD tripping from moisture ingress — the source found and put right, which is the bit that actually matters.
Getting it sorted
Renovolt covers Bridgend, Pencoed, Cowbridge, Porthcawl, Barry, Maesteg, the Vale and beyond, Monday to Saturday, 7am to 6pm. Urgent faults get prioritised and are often seen the same day.
Aled diagnoses the fault properly rather than guessing at it, tells you what it actually needs, and gives you the price before doing the work. Any call-out is agreed in writing beforehand, so there is never a surprise on the bill.