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If this is in a ground floor bathroom, you may need to pull up some floor boards to access and wire up. 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. 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. 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. 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.
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. 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 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. 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. 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.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. 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. The final job is to then do the finishing works. If you have created any chases these need to be filled. 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 with the steps above, either a shower isolator switch is used that is normally installed outside the bathroom above the door or it’s possible to use a 3-pole pull cord switch that is usually installed in zone 3 inside the bathroom. 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.
Types of Bathroom Fan Switch Configuration
When connecting up, its necessary to ensure the brown is connected to the permanent live terminal in the junction box and the common (C) in the switch, and the blue cable (sleeved brown as it is not being used as a neutral but as a live conductor) is connected to the SL (switched live) terminal in the junction box and L1 in the 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. 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.
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