I have had a kitchen extractor fan isolator switch fitted Im not sure if it makes a different to which type ofv fan I buy, does it matter if I buy a fan withought a pullcord? I dont want to have the electrics changed again. currently there is an isolator switch fitted with some cable hanging out the wall and would a person (non electritian) be able to wire up the fan after the hole is made in the wall or does it require an expert?