Finally, connect the pull-cord switch that wil be used to turn the fan on and off into the junction box using normal 2-core cabling as with any other light switch. For both different types of units they can also be tuned on and off through normally 2 different means; they are either wired into the light, so that when it’s turned on the extractor comes on also or they have their own dedicated switch, normally as an isolator outside the bathroom above the door or inside as a pull cord switch.

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. As it’s in a bathroom, although it’s not required, the belt and braces approach is to fit a 3-pole isolation switch so that all potential live points; permanent live, switched live and neutral are isolated when the switch is turned off. Firstly the supply from the 3-pole isolator switch should be connected in to the junction box using a suitable 1mm or 1.5mm twin and earth cable to the L, N and E terminals. With most fans there will be 2 or 3 different settings that can be used. Once this is done, the circuit is isolated once more until the finish is completed. He then writes up and issues the works installation certificate.If you are installing an inline fan then you will also need to install the associated pipework that will carry the moist air from the source to the outside.

A larger diameter hole (stated in the instructions) is drilled in the ceiling above the shower, bath etc. and the vent is inserted and fixed up after the end of the pipework is fixed. The same is done at the other end in a suitable location to vent the moist air, normally through a soffit closer or fascia board. When connecting up the pipework make sure that you first tape the pipe to the fan body using aluminium tape and then also screw up a large jubilee clip around the pipe. This will ensure a full and compete seal. In terms of each end when installing an inline fan, you will need both internal and external extractor fan vents.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. If installing an inline fan, this will need to be positioned and screwed down to a flat and level surface, ideally between the point that air is being extracted and then being expelled. If this is in a ground floor bathroom, you may need to pull up some floor boards to access and wire up. This briefly covers the 2 main different types of extractor but for a full and detailed run down, see our types of extractor fan project here. Types of Bathroom Fan Switch Configuration

In this instance, the switch live (SL) connection is not used but it is recommended that a 3-pole switch is still fitted as it would allow the circuit to be reconfigured to work with the light switch in future if desired. If however an axial fan (one through the wall) is being installed this will need to go on an outside external wall. 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. The wiring diagram below shows the wiring setup you need to connect your new timed fan to your existing light circuit ceiling rose so that when the light is turned on, so is the fan.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. Before anything is done at all the very first job is to isolate the power to the circuit you will be working on! This means pulling out the fuse or turning off the MCB for the lighting circuit the bathroom light is getting power from. When it comes to the cable that should be used, as extractor fans are low voltage it’s possible to use 1mm or 1.5mm cable. Also, for timed unit extractor fans, as there is an extra cable you can use 3 core and earth, however if wiring a standard fan with no timed switch, 2 core and earth is fine. The other end is connected to the timed fan terminals as stated by the manufacturer in the instructions provided with the unit.