Extractor fans for bathrooms will have a timer built into it so that the fan can run on after the lights have been turned off to clear the room of steam. They require the following connections for this. A permanent live wire for the timer in the fan, a switch wire from the lights to start the fan running and a neutral. The permanent live can be connected to the Com of the pull cord and the swiched live from L1 of the pull cord. Take a neutral connection from the main lighting circuit, you will need a junction box for this if there is not already one been used. When you purchase a complete fan kit for a bathroom it will have a wiring diagram with it. The alternative is to use a seperate pull switch to control the fan as this will minimise its use for showers and baths only.
baz, December 2007
