If you want to control a light fixture or
receptacle from more than one location or switch, you will need
to use a 3-way light switch. For example, to operate a
light in a stairway from both levels of a house.
There are three terminals on a 3-way switch. One is dark or
black in color. This is called the common. The other two are
brass or gold in color. These are called travelers. A normal
single pole switch is either on or off. However, a 3-way switch
switches the common terminal between one traveler terminal to
the other traveler terminal.
Lock out the panel box, so no one can accidentally turn the power back
on while you are working.
Wires- If you are using aluminum wires in this situation, it is very important
that you use fixtures and/or wire connectors or wire nuts that are UL (Underwriters
Laboratories) approved for use with aluminum and copper wires.
1) Wiring a 3-way light switch system
Wiring a 3-way switch is a simple step once you
understand how a 3-way light switch system works. Notice the figure below.
Looking at the drawing you will notice that there are 3 sets of
1). One cable
bringing in power.
cable going to the light(s).
3). One cable connecting both 3-way switches.
The cable connecting both 3-way switches is a 3 wire cable. This
means that there are actually 4 wires in the cable. Black, red, white,
and a ground wire. The black and red wires are both connected to the
traveler screws on the switches. It doesn't matter which one goes where.
As you can see they're both the same.
Although there are many different ways a 3-way light switch system can be
arranged, they're all wired the same. Example: The power cable may
not come in the same switch box as the cable going to the light. One
could go in one switch box and one in the other. However, it's still
wired the same. The common on one switch always goes to power (black
wire) and the common on the other switch always feeds the hot (or power)
to the light. Also, the two traveler terminal wires always go to the
other two terminal wires on the other switch.
ground wire (bare copper wire or green wire) to the ground screw of the
switches. If more than one
ground wire is in the box, twist them together along with a pigtail
with a wire connector (wire nut) or a crimped connector. Next, attach the pigtail ground wire to the ground screw on the
receptacle. If you are using a metal outlet box, make sure a pigtail ground
wire is connected to the ground screw on the box.
NOTE: Before putting the cover plate on the switches, make sure the
switch is aligned straight vertically before you tighten it down (to be
visually pleasing). Also, do not over tighten the screws
for the cover plate, as it may crack.