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When it comes to the type of extractor fan found in a bathroom there are essentially 2 different types; time switched and non-time switched. The main difference between the 2 is that with a timed switch, when the unit is turned off it will run on for a set amount of time to finish clearing the bathroom and when the time expires it then turns itself off. In terms of each end when installing an inline fan, you will need both internal and external extractor fan vents. 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. 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.
If this is in a ground floor bathroom, you may need to pull up some floor boards to access and wire up. Firstly the cable is capped over using a PVC capping or piece of trunking. This then protects the cable in the wall. In terms of zones and where a switch can be fitted, this is generally best done in an area of zone 3, but you have to ensure that the correct rating of switch is also used, but your electrician will know for sure what to use. Tools and Products Needed to Wire a Timed Extractor Fan For completeness we will also cover how a standard bathroom extractor fan is wired up to it’s own switch and not an existing light switch. Wiring a Timed Extractor Fan That’s Turned on by an Existing Light Switch 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.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.
Once isolated, the next job is to install the fan isolation switch/3-pole switch. Where this is done will depend on the switch you have. When wired to its own switch, the switch itself will either be located outside of the bathroom, normally above the door or it can be inside as long as it’s in the correct zone and is a pull cord switch. 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. Another point to be aware of is that in many installations a 3-pole isolation switch is fitted to the fan to allow it to be totally isolated from its electrical supply in the event it needs maintenance work.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. Despite this, if you are unfamiliar with working on and around electricity then you are better off getting the pros in to do it for you! Wiring a Timed Extractor Fan Switched on by its Own Switch 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 motor is IPX5 rated("resistant to jets of water from all angles"). This means it can be installed in any zone of the bathroom without the need for a separate transformer.
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. The final job is to then do the finishing works. If you have created any chases these need to be filled.
Types of Bathroom Extractor Fan Power Supply
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 however an axial fan (one through the wall) is being installed this will need to go on an outside external wall. 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. In a similar manner, the junction box for the live feed is then wired to the FCU, again, each wire connected to the correct live, neutral and earth terminals.
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