# Ceiling Fan Wiring

Discussion in 'Electrical Forum discussion & Blog' started by David D, Mar 28, 2008.

1. ### David DNew Member

Joined:
Mar 27, 2008
I have a SMC fan motor with four wires,by pairing two sets of wires I'm able to run the motor CCW, changing the pairing will run the motor CC.
I'm wanting to add the capicator to increase the speed.
Where would the capicator be incerted t odo this

David D

2. ### jwelectricElectrical Contractor/Instructor

Joined:
Jun 14, 2007
Occupation:
Instructor
Location:
North Carolina
cap won't increase speed

4. ### Bill ArdenComputer Programmer

Joined:
Sep 30, 2006
Occupation:
computer programmer
Location:
MN, USA
Some celling fans will run faster if you shorten or flatten the blades.

Try running it without the blades to see what it's unloaded speed is.

5. ### jwelectricElectrical Contractor/Instructor

Joined:
Jun 14, 2007
Occupation:
Instructor
Location:
North Carolina

by doing this to gain more speed will the fan move more air or will the air flow be about the same

6. ### Bob NHIn the Trades

Joined:
Oct 20, 2005
Location:
New Hampshire
The POWER (Watts) required by a fan varies approximately (theoretically) as the third power of the speed. Therefore, increasing the speed by only 10% increases the power requirement by 1.1 cubed = 1.331; or an increase of 33 percent. Since power= Volts x Amps, that means you need 33% more Amps.

Now resistive heat loss in the windings varies as current squared x resistance. The resistance is approximately constant, (actually increases slightly with temperature), so the heating increases as Amps squared, or 1.33 squared = 1.77. That means that a 10% increase in speed will increase the heating in the windings by 77%.

If you increase the heating in the windings by 77% you will eventually cause failure of the insulation of the windings. That will produce a short circuit - much sparks and smoke - until it (you hope) trips the circuit breaker.

Now, you are the one to decide if you really want to increase the speed of the fan motor.

7. ### David DNew Member

Joined:
Mar 27, 2008
The capicitors ,1.5 and 3.0 UF were initially in the circuit through a three position switch. I don't know how to wire them back into the circuit.

David D.

8. ### David DNew Member

Joined:
Mar 27, 2008
Bob,
This fan came with a three position pull switch. when I received it the wiring was already dismantled. I can pair the fan wiring to made the fan run CW or CCW.
I don't know how to wire the capicator in to chane the speed

9. ### Bob NHIn the Trades

Joined:
Oct 20, 2005
Location:
New Hampshire
Your first post on 3/28 said that you wanted to insert a capacitor to increase the speed.

My post on 3/30 was in response to that first post. It explained why increasing the speed beyond the maximum speed for which the fan and motor were selected or designed will result in destruction of the motor and could cause a fire.

If you are simply trying to replace capacitors to restore the fan/motor to an original factory condition, we don't have enough information to give you that answer.

10. ### jwelectricElectrical Contractor/Instructor

Joined:
Jun 14, 2007
Occupation:
Instructor
Location:
North Carolina
I do!

Throw the junk away and buy a new fan.