Your extractor fan has stopped working. This guide covers every common cause — from a switched-off isolator to motor burnout — tells you what to check yourself, and explains when you need an electrician.
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Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.
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You switch on the bathroom light, wait for the familiar hum of the extractor fan, and nothing happens. Or the fan in the kitchen has gone silent. A non-working extractor fan is one of the most common electrical issues in UK homes — and while it might seem minor, it affects ventilation, condensation, and can indicate a wiring fault.
The good news is that many extractor fan problems have simple causes. The isolator switch may have been turned off accidentally, the timer relay may have failed, or the humidity sensor may need cleaning. Some causes are more serious — wiring faults, motor burnout, or a tripped circuit breaker can all stop a fan from working.
This guide covers every common cause, explains the difference between bathroom and kitchen fan types, tells you what you can check yourself, and explains when you need a qualified electrician. If you are an electrician, the later sections cover fault finding techniques specific to extractor fan circuits.
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Before calling an electrician, run through these checks. They catch the most common causes and could save you a call-out fee:
Every extractor fan should have an isolator switch. In bathrooms, this is usually a pull cord on the ceiling or a switched fused connection unit outside the bathroom. Check that it is in the "on" position. Pull cords can be accidentally turned off, and family members may have switched off the isolator without realising it controls the fan.
Look at the consumer unit (fuse board) and check whether any circuit breakers have tripped. The fan circuit may share a breaker with the lighting circuit. If a breaker is in the middle or "off" position, try resetting it. If it trips again immediately, there is a fault — do not keep resetting it.
If the fan is supplied through a fused connection unit (FCU), check the fuse inside it. Pull out the fuse carrier and inspect the fuse — replace with a 3A fuse if blown. The FCU is usually mounted on the wall near the fan or just outside the bathroom door.
With the fan switched on, listen carefully at the fan grille. If you can hear a faint hum but the fan is not spinning, the motor is receiving power but the bearings have seized or the impeller is jammed. This means the fan unit needs replacing — a humming, non-spinning motor will overheat if left connected.
If the quick checks above have not identified the problem, one of these faults is likely responsible:
Bathroom and kitchen extractor fans serve different purposes and have different technical requirements. Understanding the differences helps you identify problems and communicate effectively with your electrician:
Bathroom fans extract moisture-laden air to prevent condensation and mould. They are typically axial fans (100mm or 150mm diameter) mounted in the ceiling or external wall.
Kitchen fans extract cooking fumes, steam, and grease-laden air. They range from simple wall-mounted axial fans to integrated cooker hoods with centrifugal fans.
The type of switch controlling your fan affects both the possible faults and how the fan is wired. Understanding which type you have helps narrow down the problem:
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A non-working extractor fan is not just an inconvenience — it may mean your property does not comply with Building Regulations Approved Document F (Ventilation). This matters for your health, your property, and if you are selling or renting.
For landlords, a non-working extractor fan in a bathroom or kitchen can be flagged during an EICR or a local authority inspection. It may also contribute to condensation and mould issues, which fall under the Homes (Fitness for Human Habitation) Act 2018.
If the quick checks (isolator, consumer unit, fuse) have not resolved the problem, you need an electrician. Here is the urgency scale:
When the electrician visits, they should test for voltage at the fan terminals, check the switch and wiring continuity, inspect the fan motor condition, and verify the timer and sensor functions. If the fan needs replacing, they should ensure the new fan meets the IP rating requirements for the location and the extract rate requirements of Part F.
Extractor fan call-outs are bread-and-butter work. A systematic approach saves time and ensures you catch the actual fault first time:
Isolate at the consumer unit, remove the fan cover, and identify the terminals. Re-energise and test for 230V between L and N with the switch on. Test both the permanent live (should be live whenever the isolator is on) and the switched live (should be live when the light/switch is on). No voltage on permanent live? Check the FCU fuse and wiring back to the junction box. No voltage on switched live? Check the light switch connections and the switch wire.
If voltage is present but the fan does not operate, the internal timer relay or humidity sensor has likely failed. Test by bridging the switched live to the permanent live briefly — if the fan runs, the timer/sensor circuit is the fault. Many fans have replaceable timer modules; others require full unit replacement. Check the timer adjustment potentiometer has not been turned to minimum.
If the fan trips the RCD, disconnect the fan and test insulation resistance on the cable (500V DC, L-E and N-E). Minimum 1 megohm. If the cable passes, the fault is in the fan unit itself — moisture ingress into the motor is common, particularly in ceiling-mounted bathroom fans where condensation can track along the duct. Replace the fan and check the duct for condensation traps. Under Regulation 411.3.3, additional protection by an RCD with a rated residual operating current not exceeding 30mA is required for circuits in locations containing a bath or shower.
When replacing a fan, ensure the new unit meets the IP rating for the zone, matches or exceeds the Part F extract rate, and is compatible with the existing wiring configuration (2-wire, 3-wire, or 4-wire). Issue a Minor Works Certificate for the replacement. Test RCD operation after installation.
Elec-Mate lets you issue Minor Works Certificates on site with pre-filled templates for fan replacements.
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