|Common Methods for Wiring 3-way |
and 4-way Switches
Below are common methods of wiring up three-way switches that were taught
to me by the master electrician I worked for many years ago (late 80s/early 90s).
The graphics and images were created about 6 years ago.
The page was re-vamped in 2006 to finally include a few real pictures.
The below descriptions are for informational use
only, if you are unsure about what you are doing when it comes to
wiring then find a licensed electrician in your area to assist
you. The money you pay will be worth the piece of mind you will
get knowing it was done right.
Replacing Existing Switches:
Read the below description FIRST before removing any wires. It is
often times difficult to determine which wire should go onto which
terminal of the replacment switch.
Knowing the 'travelers' and 'point' of the existing switch will make
replacment much easier'.
This is were the power (HOT and NEUTRAL) is coming from.
|| This is the wire that comes from what ever is to be
switched. It could be a switched outlet, an overhead light,
or recessed lighting.
|| This is a switch that has three terminals (screws) on
it, excluding the ground screw (if present).
It is used to switch a light from two different
This is the part that often confuses the novice ("Why is it
called a three way if you only use two of them?").
One of the terminals
will be a different color than the rest.
This is the 'point' or 'common'.
|| On three-way switches they are the two like-colored terminals
(screws). The wires that are connected to these terminals are referred to
as the 'travelers'. In the diagrams below, the travelers will always be
the RED and BLACK wires of a 14/3 cable.
|| This is the third (usually black) colored terminal on a three-way
|| This is a switch that has four terminals on it, excluding
the ground wire. It is used between two three-way switches to control a
light from a third (or more!) location.
|| This is a three conductor (14 gauge wire), excluding the ground
wire, cable. The wire colors are almost always RED, BLACK and WHITE.
|| This is a two conductor (14 gauge wire), excluding the ground
wire, cable. The wire colors are BLACK and WHITE.
The ground wire is not shown in any of the diagrams. Check your local
|The Standard Method
|This is the way I was taught
You may be wondering what makes a three-way switch work. If so you
are not alone. The internals of the three way switch does all the
work. When the switch is moved from one position to another, the internal
connection switches from one of the traveler terminal to the other.
Find the labels Internal Connection in the diagram above. The
light is off.
Now, in the diagram below the Internal Connection of the
second switch has been "thrown" which completed the circuit turning the
Follow the circuit from the black LINE side through the internal connection
in the switches to the switch leg.
Now the only other thing to consider is different configurations of where
the switch leg and line come into the switch boxes.
This diagram shows how to wire things up when both the switch leg
and power come into the same box.
What may concern you in this diagram is that black of the
switch leg is connected to a white wire. This white wire will be
live when the circuit is complete. A white wire carring line voltage is
only "code" (that is, allowed by the electrical code) when it is
being used in a switch situation.
It is also the most common
method used by electrians to identify
a switch leg.
Note: When you see a black and white connected
one COULD be a switch leg.
Note that the 2000 NEC code now requires that this wire be marked (usually
with black tape) as to not confuse people.
received an email (09/2003) that stated that updates to the code
require painting or marking with permanent marker the white wire when
used in the above fashion.
The next case is when the Feed and switch leg all come into a separate
box (for example a ceiling box for an overhead light).
A switch leg (14/2) is run from that box to one of the three-way switches.
Now lets throw a four way switch into the picture.
The terminals on the four way switch will be labeled to let you know
which ones to connect to each leg of the travelers. The third (white) wire
in the 14/3 is connected up as to just pass through.
What happens when the four way switch is flipped is the internal connections
are reversed. That is, if, internally:
S1's RED was connected to S2's RED and
S1's BLACK went to S2's BLACK (as shown),
switching the four way will cause S1's RED to go to S2's BLACK and
S1's BLACK to S2's RED.
either make or break the circuit (in the diagram, it will complete the