This diagram shows two switches in the same box with two separate 120 volt sources. Three-wire cable is supplying the source for both switches with the black and red wires going to the bottom switch terminals. The black wire from each light is connected to the top terminal of their respective switch. The white and ground wires are spliced to run to each light fixture.
Use this wiring when the power source originates at the switch and you want to control both the fan and light from there. The hot source is connected directly to the bottom terminal on the switch. Two-wire cable runs from there to the ceiling fan.
The hot wire to the fan in a fan/light kit will usually be black and the light wire will be blue. The white wire is usually the neutral which is always connected directly to the source neutral, either at the source or through a splice in the switch box. The white wire may also be used to carry current when necessary.
To wire an exhaust fan to a wall switch, use this diagram. These fans usually come with a small electrical connection box welded to the side of the housing. There will be a cover on the connection box that fastens with a small screw. Open it, pop the plug out of one of the wire holes and thread a wire clamp into it.
This wiring arrangement allows for lowering the lights with a dimmer and controlling the fan with the builtin pull chain. The source is at the ceiling outlet box and 3-wire cable runs from there to the switch box. The neutral from the source is spliced directly to the white wire on the fan kit and the cable, running it through to the switch box.
Here the source is at the fan/light and a switch loop runs to the wall switch. The source is wired directly to the fan and spliced through to the switch. With this arrangement the light is controlled with the switch and the fan is hardwired for pull-chain control.
In this wiring, a switch and receptacle are in the same box and the switch controls the power to the outlet. The hot wire connects to the bottom terminal on the switch and the top output goes to the receptacle hot terminal. The neutral wire from the source connects directly to the receptacle neutral.
Use this wiring when the source is at the fixture and you want to control the feed to both components with the same switch. Three-wire cable runs from the fan to the switch box and the source neutral is spliced to the white wire and to the fan neutral.