1. 1
   2
2. 3

Despite its name, you need only two switches for a three-way switch circuit.

1. hot
   neutral
2. cold

The wire carrying the current is commonly known as the "hot" wire.

1. 2
   3
2. 4

Three wires run through Romex: two insulated wires, each a different color, and one bare grounding wire.

1. plastic
   metal
2. rubber

The Romex sheath is made from plastic to keep it well insulated.

1. appliances
   ground
2. fuse box

All outlets and switches are wired to the fuse box.

1. 14-gauge
   20-gauge
2. 26-gauge

Romex for household use is normally 12- or 14-gauge Romex.

1. It has an extra ground wire.
   It has a wider sheath.
2. It has an extra insulated wire.

The special Romex needed for a three-way switch has an extra insulated wire in a different color to the normal two.

1. It allows you to dim the light.
   It allows you to control the light from two switches.
2. It allows one light switch to control three different lights.

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.

1. Both positions can turn the light on and off.
   The switch is inaccessible.
2. It is important for the electrician to figure it out by himself.

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.

1. three positions each switch can be set to
   three terminals in the switch
2. three switches in the circuit

A three-way switch gets its name due to the three terminals in each switch.

1. between the power source and the first three-way switch
   between the two three-way switches
2. between the second three-way switch and the light

You would put three-way Romex between the two three-way switches, and normal Romex in the rest of the circuit.

1. turn off the switch
   turn of the power
2. remove all light bulbs from that circuit

Make sure the power to the light circuit is switched off from the fuse box before doing any electrical work.

1. an ohmmeter
   a continuity detector
2. both of the above

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!

1. You wouldn't be able to turn the light on at all.
   The other three-way switch would now act as a normal switch.
2. The circuit would blow the fuse.

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.

1. series
   parallel
2. either of the above

Depending on how the circuit is arranged, it can be set up in series or in parallel.