On Jun 1, 12:44*pm, Bill McKenzie wrote:
I am trying to install a combination light/fan/heater in a bathroom.
There are already 2 sets of wires going from the switch box to the
ceiling location, but I need 3 (one for each light, fan, heater).
Would it be OK to share a single neutral for all three devices and use
the extra white wire in the second cable as an additional hot? *The
two cable are different colors (black and white) and the black seems
to have larger gauge wire than the white. *Any help appreciated.

It's ok, that's what is usually done. Just make sure you know which
wire is which.
Are you sure the black wire is larger than the white? Both are usually
the same guage in a romex or BX wire.
You should also have a ground wire. And this device should be on its
own circuit since a heater is involved. At least 12 guage wire.