l have just put up a extractor fan with timer in the bathroom.l have connected it up from the ceiling rose using the light switch as means of control.From the ceiling rose it goes to a triple pole isolating switch then to the fan.What l would like to know is can l put a pull cord in the circuit before the isolating switch so l can switch the fan of if l don't want it on with the light. If l can how would l do this.