bathroomexhaust-fanwiring
I am replacing a bathroom vent, light, heater combo.
The wiring from the house has three switches, but has only two lines with three wires (black, white and ground). The new vent, light and heater has 2 wires (colored and white) each function and ground.
How do you wire this configuration?
No way from here to know which wire fed the light or fan, but you have a continuous hot feed into the box that fed the receptacle, light and fan. The third wire, maybe it fed the fan or maybe something something else farther down the line, if the latter that needs to be tied in 100 percent to the hot feed. All whites still tied together, blacks to the dimmer from the light and hot. All grounds tied together set with a screw to the metal box. Securing the ground to the box is not needed if the box is plastic.
Before I got too wordy, here is a sketch
Still have to learn to format better
The sketch is a little rough, it should get the idea across I hope
Please excuse my MS Paint representation, but it should help.
From what I understand, the grounding wires may not be necessary, but if the fixtures have ground wires or grounding terminals, it can only help to connect them. This question explains grounding in some more detail.
One exception is that if the vent is directly over a shower, it might need to be GFCI protected (see this question). This could be done in a variety of ways. You could install a GFCI breaker and run the vent on a dedicated circuit, but that would be annoying if it tripped since you could only reset it at the breaker. You may be able to install a dedicated GFCI outlet in the bathroom and connect the vent and switch to the protected side of that outlet. You can also find combination GFCI outlet/switches that would combine the GFCI outlet and the switch into one unit.
Best Answer
Not counting the ground wires, you have four insulated conductors. One could be the supply hot, each of the others could be switched hot leads. The presumption would be that the neutral is in the ceiling box and not present in the wall box. Totally possible. If this is true, please mark the switched hot leads appropriately.