Wire a bathroom extractor straight into the light switch and the first thing the next electrician does on a callout is ask who fitted it. A fan isolator isn't optional extra polish, it's the bit that lets anyone turn the fan off without going near the consumer unit.

Why does an extractor fan need its own isolator at all?

Most domestic extractors run off the same circuit as the room light, which is convenient for installation but means there's no way to isolate the fan on its own for maintenance or replacement without killing the lighting too. A fan isolator switch sits between the supply and the fan, giving an independent on/off point.

It also matters for anyone other than the original installer. A maintenance engineer servicing a hotel extractor in a 40-room property in Bournemouth shouldn't need a wiring diagram to find a safe isolation point. That's the entire job of this switch.

3A or 6A: which fan isolator do you actually need?

The rating has to match the load, not the room. Most bathroom and en-suite extractors draw well under 50W, which a 3A isolator handles comfortably. Kitchen extractor hoods, utility room units, and anything with a heater element built in (some combined extractor/heater units do) need the 6A rating.

Pull-cord or standard switch: where does BS 7671 actually require one?

This is the part that trips people up. BS 7671 Section 701 governs locations containing a bath or shower, and splits the room into zones. Zone 1 (directly above the bath or shower) and Zone 2 (the 0.6m surround) require any switch to be either out of reach, IP-rated appropriately, or operated by an insulated pull cord.

A pull-cord fan isolator is the standard answer because it lets you mount the switch mechanism outside the room, or within it but operated without touching exposed metalwork, while keeping the cord accessible from inside. Outside zones 1 and 2, in a hallway or outside the bathroom door entirely, a standard moulded or grid-module isolator switch is perfectly compliant and far less visually intrusive than a dangling cord.

For a kitchen extractor hood, there's no bathroom zoning to worry about at all, so a standard switched fused connection unit or grid module isolator is the normal specification.

Pull-cord vs grid module isolator: which actually looks better and which lasts longer?

For a boutique hotel refurb where the bathroom switch plate needs to match the room's finish, the answer is usually both: pull-cord inside the wet zone for the fan, grid module isolator outside the door for everything else on the same circuit run.

What IP rating does a fan isolator need in a bathroom?

If the isolator is mounted inside Zone 2, it needs a minimum of IP44 to handle splashing. Outside the zoned area, in a hallway or utility room, standard IP20 indoor-rated switches are fine, there's no splash exposure to design against.

Pull-cord isolators are commonly rated IP20 themselves because the switch body sits outside or above the zone, with only the cord passing through, but always check the specific product's IP rating against where the body of the switch will actually be mounted, not just where the cord ends up.

Frequently Asked Questions