On Oct 5, 11:50*pm, wrote:
On Wed, 5 Oct 2011 18:15:11 -0400, "John Grabowski"





wrote:
My attic gable fan (http://www.homedepot.com/buy/building-materials/
ceilings-attics/master-flow/power-gable-vent-pg3-1600-cfm-21356.html)
has a thermostat built in that kicks on when it gets too hot up
there. *The fan is powered by a dedicated BX cable that runs up to the
attic, and this cable has a regular wall switch that I can shut on/off
from the 2nd floor hallway. *I want the option to run the fan manually
too, bypassing the thermostat. *I can replace the BX calbe with a
4wire cable (two hot/one neutral/one ground), and have one of the
wires bypass the thermostat.

But, what kind of wall switch would I need to buy that has, basically,
three settings: off, on (for automatic fan operation via thermostat),
and on (for manual operation of fan, bypassing thermostat)?

*You could use a combination device with one single pole switch and one
three way switch. *The single pole would serve as the on-off and the three
way will change it from thermostat to always on.

http://www.legrand.us/passandseymour...on-devices/sta...

I think this combination is also available in Decora style. *Go to an
electrical supply company to get one.

3 way not required. Sw 1 powers the thermostat through the black wire.
Switch 2 powers the fan (fan side of 'stat" through the red wire, from
the black wire at the switch. Sw1 on means the fan is on thermo, Sw1
AND Sw1 on means fan on direct. Sw2 only on, fan is off- Hide quoted text -

- Show quoted text -

Inquiring minds want to know..... Why does the OP
want to run the attic fan without the attic being hot?
Mine is wired with a switch in series with a thermostat
on the fan, just like his is now. Works fine for me.
Some places it's desirable to have them run for
dehumidification, but for that you wire in a control
that measures temp and humidity.

If he does want the option of running it when it's not
hot, then the SPDT switch is the way to go. It's
simple and won't look like a hack job, which is what
he'll have with two switched, sided by side.