Tuesday, September 3, 2013

How Do Two Switches Control The Light & Fan Of A Ceiling Fan







Ceiling fans and lights operate independently using two switches.


Ceiling fans that include a light may be controlled by separate switches on the wall. One switch operates the light, the other operates the fan. In addition, two pull chains on the fan may also turn the fan or light on and off. Understanding how the two wall switches work is important for wiring ceiling fans with lights.


Single Pole Switches


Standard on-off switches are single pole switches. They have two connections, or terminals, which connect to the circuit's hot wires. When the switch is on, it acts as if it were part of the wire and conducts current. When the switch is off, it acts as if the wire were broken and does not conduct current.


In a typical circuit, electricity from the circuit breaker box is supplied to one terminal of the switch. The other other terminal is wired to a device such as a ceiling fan, light or electrical outlet. Electricity returns to the circuit breaker box through a neutral wire to complete the circuit.








Switch Wiring Box Has the Hot Wire


The hot wire from the circuit breaker ends in the switch wiring box. Two short wires connect to the hot wire and each is then connected to a separate switch, one for the ceiling fan light and the other for the ceiling fan motor.


A wire runs from the second terminal of each switch to the ceiling fan wiring box where wires from the ceiling fan lights and motors connect to the respective wires from the switches.


Neutral wires from the ceiling fan light and motor connect to a neutral wire in the ceiling fan wiring box. The neutral wire runs back to the switch box and connects to the neutral wire that runs back to the circuit breaker panel.


Ceiling Fan Wiring Box Has the Hot Wire


The branch circuit wiring from the circuit breaker panel ends in ceiling fan wiring box. The hot wire connects to another wire, which runs to the switch wiring box. In the switch wiring box, the hot wire connects to two shorter wires, each of which connect to a separate switch for the ceiling fan motor and light.


A wire runs from the second terminal on each switch back to the ceiling fan wiring box where the wires connect to the respective motor and light wires from the ceiling fan.


The neutral wires from the fan motor and fan light connect to the neutral wire in the ceiling fan wiring box which then runs back to the circuit breaker panel.


Ceiling Fan Pull Chain Switches


The ceiling fan's pull chains operate the light and the fan. They may allow the fan motor to operate at different speeds and turn on a different combination of ceiling fan lights, if it has more than one light. If the wall switches are in the off position, the pull chains cannot turn the fan or light on or off. They only operate the fan if the wall switches are on. However, changing the pull chains when the wall switches are off does change the switch positions, and the change will take effect when the wall switch is turned on.

Tags: circuit breaker, neutral wire, wires from, pull chains, wall switches, breaker panel