If you are using a standard 3-pole pull cord switch, the switch is generally fixed to the ceiling and wired down from the top. However, this is normally when it’s being installed in an upstairs bathroom and there is decent access to the top of the ceiling from the loft. From the fused connection unit the installation must then have a 3-pole isolation switch that provides at least 3mm of separation on ALL live conductors when the switch is off.

A 4-termial junction box is required to connect up the fan, 3-pole switch and the pull switch, and is wired similarly to a ceiling rose or light junction box, utilising connections for earth, neutral, (permanent) live and a switch-live. As we have stated above, if an extractor fan is being installed from scratch then this will need to be done by a qualified Part P registered electrician. However is you are simply replacing an existing broken unit then you are able to do this yourself. Extractor Fans with an integral timer or timed switch need a 3-core and earth supply to allow the unit to run on after a light is switched off. If this is in a ground floor bathroom, you may need to pull up some floor boards to access and wire up.However, if you are simply replacing an existing extractor fan because it’s broken down or failed then you are allowed to do this under Part P. As we have briefly touched on, there are 2 main methods for turning a bathroom extractor fan on and off. You can either wire it into the bathroom lights so that when they are turned on the fan comes on at the same time or you can wire it to its own switch. Once the fan is positioned, the next task is to get it wired up. A suitable length of cable is cut to run from the 3-pole switch out to the fan. Again, if installing a axial fan through the wall you may need to chase out a section of wall to run the cable to the fan.

When it comes to electrical work in the bathroom, as this is regareded as a “special location” by the regulations, any electrical work can and should only be carried out by a Part P registered electrician so that it is ensured the circuit is installed correctly and to regulations standard, can be fully tested once complete and finally a minor works certificate can then be issued to sign everything off. Strip both ends of the cable to suitable lengths (manufacturer should state this in their instructions, if not see our stripping cable project here) and connect the switch end cable to the correct terminals. If you are installing an axial through the wall type fan then you may need to run a short section of pipe between the inner and outer sections so that it bridges the cavity as you don’t want to be pumping moist air down into your empty cavity as this will cause untold amounts of issues.Next, the fan itself needs to be installed. How this is done will depend entirely on what type of fan is being installed. Although not necessarily required by the regulations, it’s still a great idea to do. Also, ensure that you do actually use a 3-pole isolation switch as they are much more complete than a standard switch as they isolate all 3 wires that need isolating; permanent live, switched live and the neutral. From the FCU, the 3-pole isolator switch is connected up using a suitable length of cable that’s stripped at both ends. It’s connected between the 2 units, neutral terminal to neutral terminal, live terminal to live terminal and earths to earths. An extractor fan is an essential part of any bathroom as it helps to remove the excess moist and humid air produced by the shower and keep any condensation build up to a minimum. This wiring diagram shows an easy to follow configuration for a bathroom extractor fan fitted with a timer, that’s not going to be turned on by the existing light switch. Instead, we are going to install a new switch that will turn the fan on and off.

It must also be possible to isolate the fan by means of a pull cord switch inside the bathroom, or a fan isolation (3-pole) switch outside of the bathroom. If it isn’t and there is no official evidence to prove it’s been done by a professional with the required qualifications then in the event of any issues it is likely that your home insurance won’t be valid and if you come to sell your home then this can again cause huge issues. Once capped over any chases are then filled using a suitable type of filler or plaster. Once dried it can then be sanded flat with the surrounding surfaces and then finally painted.Next, the fan should then be connected using 3 core and earth cable (depending on the model the earth may not be required), with the extra cable being used as the switch-live (SL). The other end is connected to the timed fan terminals as stated by the manufacturer in the instructions provided with the unit. Firstly the cable is capped over using a PVC capping or piece of trunking. This then protects the cable in the wall. As with all electrical work, before anything is done at all, make sure that the circuit being worked on is fully isolated in the fuse box or consumer unit. To do so, either pull out the fuse or turn off the MCB. Again, if you are working on the ground floor then you may need to pop up some floor boards from above to run cables and access existing lighting circuits.