You must run all the circuit conductors together, so it's probably easiest
to remove the two wire cable and run a three wire up from the switch



wrote in message
ups.com...
I want to replace a bath fan with one that has an automatic humidstat.
To do this, the fan requires three wires - white, black, and red. This
will allow the fan to be turned on manual or automatically. I only
have a white and black with the current fan. I need the red wire. Can
I:

Just run a third single red wire

or

Do I need to feed a separate three wire set to the fan (take out old
two wire)

Thanks