A bathroom exhaust fan that has stopped working is a common household problem — and in many cases, the fix is straightforward. Before you call a tradie, there are several checks a homeowner can safely carry out. However, because bathroom fans involve electrical wiring, it's important to understand where the legal boundary lies between DIY and restricted electrical work.
Why Your Exhaust Fan Might Have Stopped Working
There are several common reasons a bathroom exhaust fan stops working:
- Tripped circuit breaker or blown fuse — often the first thing to check
- Faulty wall switch — switches can wear out over time
- Clogged or dirty fan blades and grille — dust build-up can stall the motor
- Worn-out motor — motors have a finite lifespan, typically 10–15 years
- Loose wiring connection — vibration over time can loosen terminals
- Faulty capacitor — some fan motors use a start capacitor that can fail
Step 1: Check Your Switchboard First
Head to your switchboard (fuse box) and check whether the circuit breaker for the bathroom has tripped. If it has, reset it and test the fan. If it trips again immediately, stop — this indicates a wiring fault and you'll need a licensed electrician.
If you have an older home with fuse wire rather than circuit breakers, check whether the fuse has blown. Replacing fuse wire is restricted electrical work under New Zealand law — call a licensed electrician.
Step 2: Test the Wall Switch
A faulty switch is a surprisingly common culprit. You can test this by using a non-contact voltage tester (available from Bunnings or Mitre 10) to confirm power is reaching the switch. Do not open the switch or touch any wiring — in New Zealand, replacing or rewiring a switch is restricted electrical work under the Electricity Act and must be carried out by a registered electrician. See the Electrical Workers Registration Board (EWRB) for details on what work is restricted.
Step 3: Clean the Fan Grille and Blades
This is the most DIY-friendly fix and is often all that's needed. Dust and lint build-up can clog the fan enough to stall the motor or cause it to overheat and cut out.
- Turn off the power at the switchboard before doing anything else.
- Remove the grille cover — most clip or screw off.
- Vacuum or wipe the blades, housing, and grille with a damp cloth.
- Check the duct outlet (usually in the ceiling or wall) isn't blocked.
- Refit the cover, restore power, and test.
A clean fan also moves air more efficiently, which matters for compliance with the Healthy Homes Standards if you're a landlord — rental properties must have adequate ventilation in bathrooms.
Step 4: Inspect and Replace the Fan Motor or Unit
If cleaning doesn't help, the motor itself may have failed. Many exhaust fan motors are available as replacement parts, or you can replace the entire fan unit.
What a homeowner can do:
- Remove the old fan grille and fan blade assembly for inspection
- Purchase a compatible replacement fan unit
What requires a licensed electrician:
- Disconnecting and reconnecting wiring to the fan unit
- Any work inside the ceiling space involving wiring
- Installing a new fan where one didn't previously exist (this may also require a building consent — check with your local council)
Under New Zealand law, all electrical wiring work is restricted. The EWRB is clear that homeowners cannot carry out wiring connections, even simple ones.
Choosing a Replacement Fan
When selecting a new fan, consider:
| Feature | What to Look For |
|---|---|
| Extraction rate | Minimum 25 L/s for bathrooms (NZ Building Code clause G4) |
| Noise level | Measured in sones — lower is quieter |
| Duct size | Match your existing duct diameter (typically 100 mm or 150 mm) |
| Timer or humidity sensor | Useful for energy efficiency and moisture control |
Good ventilation is essential to prevent moisture damage and mould — a concern well-documented by BRANZ, New Zealand's building research authority. Persistent moisture can lead to issues covered under NZ Building Code clause E3 (Internal Moisture).
Safety Note
Always isolate power at the switchboard before touching any part of the fan. Use a non-contact voltage tester to confirm the circuit is dead before you begin. Never work on live circuits. If you're uncertain at any point, stop and call a professional. For guidance on electrical safety, refer to WorkSafe NZ.
When to Call a Professional
Call a licensed electrician if:
- The circuit breaker keeps tripping after reset
- You need wiring disconnected or reconnected
- You're installing a new fan where there wasn't one before
- You notice burning smells, scorch marks, or hear buzzing from the wiring
- You're simply not confident — there's no shame in it
You can find qualified, local handymen and electricians on tradedirectory.co.nz to get the job done safely and correctly. For work that may affect your home's structure or weathertightness (such as cutting a new duct penetration through an exterior wall), check with your local council whether a building consent is required. More information is available at MBIE Building Performance.
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