This is probably the stupid question of the week. Just about to install a nutone inline exhaust fan for three bathrooms. If I wire it with a four way switch and someone turns it on in one bathroom and someone else then goes to another bathroom and hits the switch, won’t they be turning it off instead?
How would you know if it is ever on or off since you can’t hear it? Am I missing something really obvious?
Paul
Replies
A 4-way switch is an XOR circuit. Changing the state of any switch changes the state of the circuit, as you've described. What you want is an OR circuit, where the fan is off if all the switches are off and on if any one or more switches is on.
Branch the black wire and run a separate wire to each bathroom. The fan switch in each bathroom is a normal SPST switch. The wires from the bathroom switches then converge at the fan and are all connected to the dark terminal on the fan. That way no one has to worry about turning the fan off for another bathroom still being used.
If your intention is to be able to turn on the fan from any of the bathrooms then you should wire the switches in each room in paralel with each other, though in this arrangement you would also have to turn off the fan from the switch that turned it on. There are switches that have lights in the toggle or next to it, to show if the switch is on or off. You are right about the 4-way set-up - each switch would reverse the previous action of any other switch.
There may also be a relay set-up for turning something on and off from various points, though I don't know where to look for it.
You can also get double pole switches. So you can use the switch in each bathroom to operate the lights in that bath and also the fan.