You are ready for bed and want to walk up the stairs to the bedroom. At the bottom you flick a switch to turn on the stairway lights and when you get to the top there is another switch to turn the same lights off. It's thanks to three-way switches that you can do this. Learn all about these special switches by taking this quiz.
Despite its name, you need only two switches for a three-way switch circuit.
The wire carrying the current is commonly known as the "hot" wire.
Three wires run through Romex: two insulated wires, each a different color, and one bare grounding wire.
The Romex sheath is made from plastic to keep it well insulated.
All outlets and switches are wired to the fuse box.
Romex for household use is normally 12- or 14-gauge Romex.
The special Romex needed for a three-way switch has an extra insulated wire in a different color to the normal two.
A three-way light switch allows you to control a light from two switches in different locations. This would enable you to turn the lights on your staircase on or off from the top or the bottom.
The idea of a three-way switch is that both switches can turn the circuit on and off, so the on and off position would be different each time.
A three-way switch gets its name due to the three terminals in each switch.
You would put three-way Romex between the two three-way switches, and normal Romex in the rest of the circuit.
Make sure the power to the light circuit is switched off from the fuse box before doing any electrical work.
An ohmmeter or continuity detector is the only way you can find out how your house was wired, unless you are in contact with the electrician who wired it!
Since each three-way switch independently turns the light on or off, if one gets stuck the other would still work, but it would now function as a normal switch.
Depending on how the circuit is arranged, it can be set up in series or in parallel.