Does a new duplex switch need to be used after you add a bath exh. fan in order to be able to turn the light and fan on seperately? I have added a fan and would like to tap into the light switch and have seperate siwtches for both. Need to know how this wiring is done and where the wires get hooked up at switch. Do I need to replace the old single pole with a duplex switch to control the fan and light independently? I am leary of buying duplex switch if this is not going to work----would like fan & light work seprate from one another...can this be wired into the old box and how? 2 black wires---2 white and 2 grounds are exsisting inside box. I believe the light was wired with switch inbetween source and neutral return.