Can I fit a bathroom extractor fan myself?

This is one of the clearest lines in domestic DIY. The mechanical half of a fan installation is ordinary building work. The electrical half is regulated because of where it is, not because of how complicated it is.

Safety

Step by step

1. Understand why bathrooms are treated differently.Wiring regulations divide a bathroom into zones around the bath and shower. Equipment in each zone must meet a minimum protection rating and be supplied through an RCD. Water and earth potential make faults far more dangerous here.
2. Know what Part P actually requires.In England and Wales, electrical installation work in a room containing a bath or shower is notifiable. It has to be done by an electrician registered with a competent person scheme, or notified to building control in advance and inspected.
3. Know what it does not cover.Replacing a like-for-like accessory is treated differently from new work, but a fan installation almost always involves a new supply, an isolator, or a new position. Do not assume you are in the exempt category.
4. Do the mechanical work yourself if you want to.Cutting the ceiling or wall opening, running and insulating the duct, fitting the external terminal, boarding the loft for access — all of that is ordinary work and saves real money.
5. Prepare the route before the electrician arrives.An open, ducted, terminated route with a clear path for the cable turns a half-day job into an hour. Agree the position with them first.
6. Choose the fan and controls in advance.Humidity sensing, run-on timer, in-line or axial. Buying it yourself is fine and often cheaper; just confirm the model suits the position with the electrician.
7. Insist on the certificate.You should receive an electrical installation certificate or minor works certificate, and for notifiable work a building regulations compliance certificate. Keep both — they matter when you sell.
8. Do all the maintenance yourself afterwards.Cleaning the grille, the impeller, the shutter and the duct is householder work and is what keeps a fan effective.
9. Recognise the same line elsewhere.Electric showers, bathroom lighting, shaver sockets and heated towel rail elements sit on the same side of the line for exactly the same reason.

Tips

• Doing the ducting and builder's work yourself typically saves more than doing the wiring would have.
• Agree the fan position with the electrician before you cut anything — zones and duct routes both constrain it.
• Keep the certificates with the house paperwork. Missing certification for bathroom electrics is a routine query on a sale.

Common mistakes

• Swapping a fan yourself because it is 'like for like' — Fan replacements almost always involve the isolator, the supply route or the position, which is notifiable. And an uncertified alteration in a bathroom is a problem when the house is sold or if there is ever a claim.
• Wiring a fan into a lighting circuit without an isolator — A fan must be able to be isolated for maintenance, and the run-on models need a permanent live as well as a switched one. Getting it wrong leaves a fan that cannot be safely worked on.

If it doesn't work

Questions people ask