by ericmark »
Wed Sep 05, 2012 12:32 am
The bathroom fan is only wired to light switch when either it's an extra and not required by building regs or there are no windows in the bathroom.
The simple method is a pneumatic push button which is pushed manually to activate fan. By swapping the light switch for a double pole switch you can have both push button and lights work the fan.
To take a supply from a ring circuit or any other circuit with high power you would also need a fused connection unit (FCU) to fuse down to 3 or 5 amps. It is common for a fan to go faulty so it is always a good idea to have some way to isolate it. Last thing you want is no lights because fan is faulty.
There are loads of regulations covering the fitting of a fan Part P, F, and maybe more. Any air pumped outside must be replaced and you don't want it being replaced with flue gasses so there needs to be a way for air to replace it.
Since it is notifiable work to DIY is an expensive option and far cheaper to get a scheme member electrician to do the work. This also means he does need to follow the rules. In most new houses the fan is fitted the building inspector passes the work then it is switched off never to be used again.