A fan speed control switch makes it easy to adjust the speed at which a fan spins. This is actually a fairly simply switch that is mounted on the wall. Although it seems to do a job similar to a dimmer and actually looks very similar, the fan speed switch is more like a regular light switch and will be wired in series with the fan. This can then be adjusted to change the speed of the fan.
Step 1 - Safety
Before starting work on any electrical system, you must ensure that it's safe to do so. Switch the circuit breaker off by either removing the circuit breaker or alternatively shutting off all of the power to your home. Try turning the fan on to ensure that the right circuit has been cut.
If you don't feel confident to do this work yourself, consider hiring a professional electrician to help you out. An electrician will be able to identify how to do the work safely without you needing to lift a finger.
Step 2 - Identify the Wire
If you want to install a fan speed control switch to an existing fan, you will first need to identify the wires which are supplying power to the fan. This is because you will need to cut the wires and install the switch in line with the fan. Locating this wire can be a little tricky at times, but you can normally trace the rough route of the wire.
Cut a hole into the wall along the path of the wire; the hole must be big enough to house the electrical switch box. Do this carefully so that you don't risk cutting through or damaging the wires.
Step 3 - Cutting wires
Cut the live wire where the electrical box will be fitted in the wall and push both ends of this wire into the electrical box. Try to make sure that you cut the wire in the correct place so that you have enough wire to connect into the box.
Step 4 - Mounting the Box
The electrical box now needs to be fitted into the hole in the wall. Depending on the wall that you're fitting into this will either be a matter of screwing the box in, or alternatively using drywall clamps to fix it in place.
Step 5 - Connecting the Power
Wire up the fan speed switch control switch by following the normal wiring standards. Make sure that all of the wires are first pulled through the electrical box to ensure that the face place will fit securely against the wall. The live black wires should be connected to the brass screws. The earthing wire will also need to be connected, as will the neutral wire.