Wiring whole house fan

[mlpotts]

I am currently installing a whole house fan ( I hope it's worth working in a
hot, cramped attic). The fan has a four amp motor and includes a three way
switch, hi, low and off. The motor has a large capacitor and three wires,
one each of black, red and white. I have two questions. How do I connect
these three wires to the existing house wiring of black, white and ground?
Can I substitute a variable speed control for the hi, low and off switch?

Thanks,

Michael Potts

[Daniel Hicks]

There were instructions with the unit. Follow them.

[Greenlight]

First I would follow the directions in the box that came with your switch
and fan. Barring such, I would imagine a two position switch would be in
order. Position "A" would connect the hot lead to the black, while position
"B" would connect the hot lead to the red. Position "C" would be off.

You didn't describe the switch, but I imagine that you have a three terminal
switch with 3 positions. "X" would be for the incoming power lead, "Y" goes
to the low speed connection, and "Z" goes to high speed connection. Connect
the white wire of your house wire to the white wire at the fan, "Y" would go
to "A" or "B" depending which is low speed, and "Z" would go to "A" or "B"
depending which was high speed. Be sure to connect the house ground wire
(bare or green wire) to the bare or green wire at the fan housing. Funny
that you didn't mention a bare or green wire at the fan. Is the fan new?

It seems from your incomplete description that the fan is internally wired
for only two speeds so you would need at least a SUITABLE variable speed
control to slow the fan down which must be compatible with the type of motor
which it uses. Otherwise you can damage the motor. Thus what type of motor
is it? Rather unless you know that you need to fine tune the speed (volume
output) other than from high to low, it may be better to leave well enough
alone and try first to hook it up to the low speed first in conjunction with
either a temperature sensor (thermostat) and/or humidity sensor and see how
well it works at that speed. If you need it faster hook it up to the higher
speed wire (red or black).

How did you plan on using the fan in the first place ("on" all the time) or
with what type of control/sensor? Is it rated for continuous duty? Lastly
(:-) what do the directions suggest?

mlpotts <mlp...@donet.com> wrote in message
news:LbEO4.1551$cO....@newsfeed.slurp.net...

> I am currently installing a whole house fan ( I hope it's worth working in
a
> hot, cramped attic). The fan has a four amp motor and includes a three way

> switch, hi, low and off. The motor has a large capacitor and three wires,
> one each of black, red and white. I have two questions. How do I connect
> these three wires to the existing house wiring of black, white and ground?
> Can I substitute a variable speed control for the hi, low and off switch?
>

> Thanks,
>
> Michael Potts
>
>

[mlpotts]

Thanks to Greenlight for his help, as for Mr. Hicks: I have read the
instructions completely and have viewed the video as well. In both cases my
very basic question was not answered. There are three wires on the motor
(plus a terminal for the ground). The instructions suggest using three
conductor wire with ground. How do I connect the three conductor wire with
ground to the existing wiring in my home which consists of two conductor
wire with bare ground?

I am sure this is obvious to many of you, but I thought I would ask to be
sure. It certainly was not covered in the instructions.I believe I will
follow Greenlight's advice and just go with the included switch.

Michael Potts

[Greenlight]

Michael;

The 3 conductor cable is used between the three terminal switch and the fan
(if you need the high, low, and off) otherwise you can use a regular switch
50 cent switch (just on and off) with two conductor wire (romex or armored
cable). If you want the hi/low option of the 3 position switch one way to go
is this:

Option A

Run a 12/3 romex, BX cable (if approved in your area), or MC Cable (metal
clad) from the switch box location to the fan. If you use BX or MC cable the
box will have to be metal and you will have to use special clamps and
insulating bushings designed for the cable. The 12/3 cables will have a red,
black, white, and ground wire (except for the BX cable which uses only the
armor as a ground). As an example you can connect the red of the 12/3 to the
hi and the black of the 12/3 cable to the low position terminal of the
switch while connecting the red and black of the 12/3 at the fan to the hi
and low terminals at the fan.

Then run a normal 12/2 romex, BX, or MC cable into the switch box from your
power source (panel box or junction box). Again if you use MC cable or BX
use a metal box and suitable box connectors and insulating bushings. Connect
the power 12/2 so that the hot (black wire) of the 12/2 cable connects to
the hot (common) at the switch. Now all 3 terminals at the switch are
connected. Connect the two whites together at the switch (white to white)
with a wire nut. Connect the grounds together with a wire nut and pigtail
then to a green ground screw if you have a metal box so that the metal box
is grounded).

At the fan, now you will have the 12/3 coming in. Connect the 12/3 red to
the high position of the fan (assuming they used red for high), the 12/3
black wire to the black wire of the fan (assuming low). the white to white
with a red or yellow wire nut, and the ground wire to the ground. If you
used BX then the armor will serve as the ground if the lock washer is driven
tight onto the metal housing.

The 12/3 will allow you a high and low speed option.

Option B
You can use just 12/2 cable and a normal (single position) switch if you
want only one speed. Just connect up to "either" the red or black at the
fan.

Option C

If the fan housing electrical box is large enough (rare), you can run power
in with a 12/2 cable connecting white to white at the fan, then run 12/3
down to the switch with the power leg taped black or another color), the red
leg, and the black leg). This way the switch has only one cable (12/3) but
the fan has two. Most likely option A will give you more room to work with.

Option D

This is a way to switch the power without using 12/3 cable at all, but it is
the most laborious and requires room at the fan electrical box. It may also
confuse you, so forget it if it is too complicated. It only works safely in
romex. You can bring the power leg into the switch box with a 12/2 cable and
run a second 12/2 with the switched power (hi and low switched legs) by
taping the outgoing white wire black and running it to the fan. Here hook up
the two switched legs (the black and taped black to the high and low (red
and black) terminations on the fan). Run a third 12/2 cable to the fan from
the same circuit that fed the switch and connect the white wire (neutral) to
the white wire on the fan. Connect all the grounds together (bare or green).
Tape or wire nut as a dead end the hot wire (black) of this third 12/2 cable
that brings in the neutral. Use this option only if you can not get 12/3
cable.

BTW the 12/3 and 12/2 will work for a 20 or 15 amp circuit. If you are using
a 15 amp circuit, then a 14/2 or 14/3 cable will suffice. Locate the switch
at a convenient or put it on an automatic controller/sensor. Option A would
most likely be the preferred method?

Bring the power into the switch box location

mlpotts <mlp...@donet.com> wrote in message

news:xgJO4.1762$cO.1...@newsfeed.slurp.net...

[mlpotts]

Greenlight:

Wow, what a superb, detailed answer!

Many Thanks,

Mike

[ROberto and JOni]

Yes, I've been lurking here awhile and there are the great answers and then
there are the pompous posturers who just love to cut people down about what
they don't know. At least if they are posting a question here, we can
assume they are smart enough to figure out that they need help.

Lurker

mlpotts <mlp...@donet.com> wrote in message

news:d0MO4.1867$cO.1...@newsfeed.slurp.net...

[Mark E. Kominkiewicz]

That greenlight is a good guy. I am glad you can help some of us rookies.

Thanks, again. MEK

As Will Rogers said "Everybody is ignorant, only on different subjects"

www.willrogers.org