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4 Way Switch Circuits
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WHILE EXTREME CARE HAS BEEN IMPLEMENTED IN THE
PREPARATION OF THIS SELF-HELP DOCUMENT, THE AUTHOR AND/OR PROVIDERS
OF THIS DOCUMENT ASSUMES NO RESPONSIBILITY FOR ERRORS OR OMISSIONS,
NOR IS ANY LIABILITY ASSUMED FROM THE USE OF THE INFORMATION,
CONTAINED IN THIS DOCUMENT, BY THE AUTHOR and / OR PROVIDER.
You will need...
1. A 4 wire cable that is routed between switch box 1 and switch box
2 - these wire cables comes with a black / red / blue (or white
striped) / white wire plus the bare equipment grounding wire.
2. A 4 wire cable that is routed between switch box 2 and switch box
3 - these wire cables comes with a black / red / blue (or white
striped) / white wire plus the bare equipment grounding wire.
3. A 3 wire cable that is routed between switch box 2 and the
fixture box - this wire cable comes with a black / red / white wire
plus the bare equipment grounding wire.
3. A circuit power supply source wire cable that is routed to
fixture.
4. Insulated wire nuts to connect / join wire together, variety of
sizes out there so make sure you obtain the correct size.
5. Wire staples, to affix the wire cables to wall studs as needed.
Wire cable must be secured within 6 inches of entering the
electrical box.
6. Wire cable / wire strippers.
7. Screwdrivers as required.
Holes drilled to feed wires through studs must be 1 1/4" from edge
of stud, in instances where the wire cable is closer then the edge
of stud must have a 1/16-in. thick protective metal plate over the
area where the cable is being feed through (may want to notch the
stud so that that the protective plate does not create a bump on the
drywall). Also read the article called ' Wire
Routing Basics'
Wire cables entering the electrical box - secure the cable clamp at
the box snug enough that the cable cannot come out but not too tight
as to pinch the cable and break through the insulated cover of the
cable.
You must have at least 6 inch length of wire inside the electrical
box, it can be a bit more but not less, it can fail an inspection if
the length of each wire is less than 6 inches. Also read the article
called ' Box
Fill Calculations' as there is a limit on how many
wires are allowed for a certain size electrical box.
STEP 1 - Make
certain that the power supply cable is dead - turn off the
electrical breaker at the service panel. Make certain that everyone
in the house is aware of what you are doing so that they do not get
the notion to reset the breaker when another light in the home is
not working.
STEP 2 - Make the
box openings (if a existing home)
STEP 3 - Feed /
Route the wire cables.
STEP 4 - Mount /
Install the Electrical Boxes (make sure the electrical boxes are
secured as some fixtures are heavy and may require additional
support) [The electrical box should not extend beyond the edge of
the finished wall or ceiling so that the fixture can mount flush to
the ceiling and the wall switch cover will mount flush - but it also
should not be recessed too far into the wall or ceiling]; then feed
the wire cables into the electrical boxes. Sometimes because of
tight openings in existing homes, the wire cable may to be feed into
the electrical box then the box put in position and secured.
STEP 5 - Connect
the wires...
Connections Instructions:
(as depicted in the diagrams above)
At the Fixture box...
Two cables entering this box, one is the circuit power
supply cable, the other cable coming from switch 2.
* a) using an insulated wire nut connect / join the black
wire from 'circuit power supply cable' + the red wire of the
cable coming from switch 2.
* b) using an insulated wire nut connect / join the white
wire from the 'circuit power supply cable' + the white wire
coming from switch 2 + the grounded conductor (neutral) of
the fixture - if the fixture has screw type connections then
connect to the silver color screw.
* c) connect the black wire coming from switch 2 to the
switched ungrounded conductor (hot) of the fixture itself -
if the fixture has screw type connections then connect to
the brass color screw.
* d) please see under important notes in regards to the
equipment grounding conductor (bare wire).
At switch 1 box...
One cable entering this box, coming from switch 2.
* a) connect the black wire coming from switch 2 to common
screw of switch 1.
* b) connect the blue wire coming from switch 2 to to one of
the remaining main screws of switch 1.
* c) connect the red wire coming from switch 2 to the last
remaining main screw of switch 1.
* d) using an insulated wire nut cap off the white wire
coming from switch 2.
* e) please see under important notes in regards to the
equipment grounding conductor (bare wire).
At switch 2 box...
Three cables entering this box, one cable coming from
fixture, one cable coming from switch 1, and one cable
coming from switch 3.
* a) using an insulated wire nut connect / join the red wire
coming from fixture + the black wire coming from switch 1.
* b) using an insulated wire nut connect / join the black
wire coming from fixture to the black wire coming from
switch 3.
* c) connect the red wire coming from switch 1 to the one
screw that is a matching pair of screws on switch 2 (both
the red and blue wires coming from switch 1 must go to a
matching pair of screws at switch 2)
* d) connect the blue wire coming from switch 1 to the other
screw that is a matching pair of screws on switch 2 (both
the red and blue wires coming from switch 1 must go to a
matching pair of screws at switch 2)
* e) connect the red wire coming from switch 3 to one screw
from a different matching pair of screws. (both the red and
blue wires coming from switch 3 must go to a matching pair
of screws at switch 2)
* f) connect the blue wire coming from switch 3 to the other
screw that is a matching pair. (both the red and blue wires
coming from switch 3 must go to a matching pair of screws at
switch 2)
* g) using an insulated wire nut connect / join the white
wire coming from fixture + the white wire coming from switch
1 + the white wire coming from switch 3.
***Just to clarify further -
The red and blue wires coming from switch 1 go to one set of
matching screws at switch 2 -- The red and blue wires coming
from switch 3 go to a different set of matching screws at
switch 2 - A matching set is 2 screws of the same color.***
* h) please see under important notes in regards to the
equipment grounding conductor (bare wire).
A t switch 3 box...
One cables entering this box coming from switch 2.
* a) connect the black wire coming from switch 2 to the
common screw of switch 3.
* b) connect the blue wire coming from switch 2 to one of
the remaining main screws of switch 3.
* c) connect the red wire coming from switch 2 to the last
remaining main screws of switch 3.
* d) using an insulated wire nut cap off the white wire
coming from switch 2.
* e) please see under important notes in regards to the
equipment grounding conductor (bare wire).
Important Notes:
By electrical codes you MUST have at least 6 inches of wire
in the electrical box itself, and also the wire must be able
to reach at least 3 inches outside the box, it can fail an
electrical inspection if the required min. wire length is
not met. You may have the wires a bit longer (within reason)
but they cannot be shorter. Also see the note on box fill
further down in this article.
If the fixture has screw type connectors, the ungrounded
conductor (hot) is connected to the brass color screw, and
the grounded conductor (neutral) is connected to the silver
color screw. If it has black and white wires coming from
fixture, then just connect black to black and white to
white. Use wire nuts of the correct size to join wires
together.
The wire cable running between switch 1 & switch 2 and
between switch 2 & 3 has 4 wires in it - black / red / blue
/ white (plus the bare equipment grounding wire). The wire
cable between fixture and switch 2 has 3 wire in it black /
red / white (plus the bare equipment grounding wire).
What is not shown in the drawings to avoid confusion, is
that each wire cable also has a bare equipment grounding
wire included. This wire is connected to a grounding screw
in each electrical box (if the box is metal), joined either
through the grounding screws in the box itself or via a wire
nut to the bare wire of the next cable entering / exiting
the box, it is also connected to any grounding screw (if
there is one) on the switch itself, as well as any grounding
screw at the fixture (green wires that attach to the fixture
are grounds). Now if using a plastic box, it is made of a
material that is non conductive, however some plastic boxes
have a metal strip inside that can still be used to connect
equipment grounding wires, in the event that it does not use
wire nuts to join the bare grounding wires together. The
equipment grounding wire (bare in most cables) must be
electrical conductively joined throughout the circuit. Green
wires are also equipment grounding conductors.
At the 3 way switches (switch 1 & 3) there are 3 main
electrical screws, one of these 3 screws is distinctly
different in color (perhaps darker) than the other 2. This
screw connection is called the common screw. It is very
important that in order for all the switches to work as they
are intended to that the correct wire is attached to the
common screw. Basically as depicted in the drawings one
switch has the ungrounded conductor (hot) from the circuit
power supply cable attached to the common screw, where the
other switch had the ungrounded conductor (hot) feed to the
light fixture itself.
Please also note that there are a variety of manufactures
out there that make 3 way switches so it is possible that
the switch you buy may have the common screw located in a
different spot or side of the switch then depicted in the
drawings in this article, just make sure that the wire
depicted to go to the common screw of each of the switches
is actually connected to the common screw of the 3 way
switch you bought. The other 2 wires going between the
remaining screws of one switch to the other switch does not
matter as long as one wire of the 2 remaining wires go on
each of the remaining 2 screws of the switch.
At the 4 way switch (switch # 2) there are 2 sets of
matching screws, one set will match in color and the other
set will be distinctly different perhaps darker in color, it
is important that the traveler wires (red and blue in the
design in this article) from the previous switch are
connected to one matching set, and the traveler wires going
to the next switch (red and blue in the design in this
article) are connected to a different matching set.
If there is an equipment grounding screw on the 3 way switch
it may be green in color and be separated away from the main
connections of the switch and likely part of the metal frame
that is also part of the mounting structure of the switch.
Extensions to this Switch
circuit...
Be Aware that there is a limit by code on how many wires can
be in a given size electrical box, when adding more wires to
the same box you may have to install a larger and / or
deeper box to allow space for more wires coming and out of
the box.
Here is an article / explanation in regards to box fill
calculations
'Box Fill Calculation'
The instructions here are based on the fact that the circuit
has already been wired to the configuration shown in this
article and we are now making the wiring changes for onward
power.
From the switch
locations...
.
Switch 1 Onward Options
(Only 'always on' onward power available)
Onward 'Always On'
Power...
Not shown in the diagram but the onward
cable also has a bare wire (equipment grounding conductor) that
also must be connected to all the other bare wires at the switch
1 electrical box.
Connection Instructions for
onward cable (always on state)
* a) Using an insulated wire nut, connect / join - the black
wire from switch 2 + the black wire connected to the common
screw of switch 1 + the black wire of onward cable.
* b) Using an insulated wire nut, connect / join - the white
wire of onward cable + white wire from switch 2.
Identification of wires in
onward cable....
Black - Ungrounded conductor (hot - always on)
White - Grounded conductor (neutral)
**************
Switch 2 Onward Options
Because of the large number of wires at switch 2, I decided to
not provide diagram drawings but to provide a written
explanation only.
Option 1:
Onward 'Always On' Power...
Not mentioned in the explanation bellow but the onward cable
also has a bare wire (equipment grounding conductor) that also
must be connected to all the other bare wires at the switch 2
electrical box.
Connection Instructions for
onward cable (always on state)
* a) Using an insulated wire nut, connect / join - the red wire
coming from fixture + the black wire of onward cable + the black
wire coming from switch 1.
* b) Using an insulated wire nut, connect / join - the white
wire of onward cable + the white wire from switch 1 + the white
wire coming from switch 3 + the white wire coming from fixture.
Identification of wires in
onward cable....
Black - Ungrounded conductor (hot - always on)
White - Grounded conductor (neutral)
************
Option 2:
Onward Switched Power...
Not mentioned in the explanation bellow but the onward cable
also has a bare wire (equipment grounding conductor) that also
must be connected to all the other bare wires at the switch 2
electrical box.
Connection Instructions for
onward cable (switched)
* a) Using an insulated wire nut, connect / join - the black
wire coming from fixture + the black wire of onward cable + the
black wire coming from switch 3.
* b) Using an insulated wire nut, connect / join - the white
wire of onward cable + the white wire from switch 1 + the white
wire coming from switch 3 + the white wire coming from fixture.
Identification of wires in
onward cable....
Black - Switched ungrounded conductor (hot - switched)
White - Grounded conductor (neutral)
**************
Option 3:
Onward 'Always On' & Switched Power...
Not mentioned in the explanation bellow but the onward cable
also has a bare wire (equipment grounding conductor) that also
must be connected to all the other bare wires at the switch 2
electrical box.
Connection Instructions for
onward cable (always on & switched state)
* a) Using an insulated wire nut, connect / join - the red wire
from fixture + the red wire from onward cable + the black wire
coming from switch 1.
* b) Using an insulated wire nut, connect / join - the white
wire from fixture + the white wire coming from switch 1 + the
white wire coming from switch 3 + the white wire of onward
cable.
* b) Using an insulated wire nut, connect / join - the black
wire from fixture + black wire coming from switch 3 + the black
wire of onward cable.
Identification of wires in
onward cable....
Red - Ungrounded conductor (hot - always on)
Black - Switched ungrounded conductor (hot - switched)
White - Grounded conductor (neutral)
**************
Switch 3 Onward Options
(only onward switched power available)
Onward Switched Power...
Not shown in the diagram but the
onward cable also has a bare wire (equipment grounding
conductor) that also must be connected to all the other
bare wires at the switch electrical box.
Connection
Instructions for onward cable (switched state)
* a) Using an insulated wire nut, connect / join - the
black wire from switch 2 + the black wire from onward
cable + the black wire coming connected to the common
screw of switch 3.
* b) Using an insulated wire nut, connect / join - the
white wire coming from switch 2 + the white wire of
onward cable.
Identification of
wires in onward cable....
Black - Switched ungrounded conductor (hot - switched)
White - Grounded conductor (neutral)
**************
From the fixture
location...
Onward 'always on circuit power' and 'switched power' is
possible from the fixture location.
Option 1:
Onward Always On Circuit Power...
(showing bellow the fixture portion of the circuit)
Not shown in the diagram
but the onward cable also has a bare wire
(equipment grounding conductor) that also must
be connected to all the other bare wires at the
fixture electrical box.
Connection
Instructions for onward cable (always on state)
* a) Using an insulated wire nut, connect / join
- the black wire from 'circuit power supply
cable' + the red wire coming from switch 2 + the
black wire of onward cable.
* b) Using an insulated wire nut, connect / join
- the white wire from 'circuit power supply
cable' + white wire connected to the grounded
conductor (neutral) of fixture (shown as white
in diagram) + the white wire of onward cable +
the white wire from switch 2.
Identification of wires in onward cable....
Black - Ungrounded conductor (hot - always on)
White - Grounded conductor (neutral)
*********
Option 2:
Onward switched power...
(example more than one light fixture controlled
by the same 3 & 4 way switches)
(showing bellow the fixture portion of the
circuit)
Not shown in the
diagram but the onward cable also has a bare
wire (equipment grounding conductor) that
also must be connected to all the other bare
wires at the fixture electrical box.
Connection Instructions for onward cable
(switched)
* a) Using an insulated wire nut, connect /
join - the black wire coming from switch 2 +
black wire connected to the switched
ungrounded conductor (hot) of fixture (shown
as black in diagram) + the black wire of
onward cable.
* b) Using an insulated wire nut, connect /
join - the white wire from 'circuit power
supply cable' + the white wire connected to
the grounded conductor (neutral) of fixture
(shown as white in diagram) + the white wire
of onward cable + the white wire coming from
switch 2.
Identification
of wires in onward cable....
Black -Switched ungrounded conductor (hot -
switched)
White - Grounded conductor (neutral)
*****************
Option 3:
Onward 'always on' and 'switched' power...
(showing bellow the fixture portion of the
circuit)
Not shown in
the diagram but the onward cable
also has a bare wire (equipment
grounding conductor) that also must
be connected to all the other bare
wires at the fixture electrical box.
Connection Instructions for onward
cable (always on and switched)
* a) Using an insulated wire nut,
connect / join - the black wire
coming from switch 2 + the black
wire connected to the switched
ungrounded conductor (hot) of
fixture (shown as black in diagram)
+ the black wire of onward cable.
* b) Using an insulated wire nut,
connect / join - the white wire from
'circuit power supply cable' + the
white wire connected to the grounded
conductor (neutral) of fixture
(shown as white in diagram) + the
white wire of onward cable + the
white wire from switch 2.
* c) Using an insulated wire nut,
connect / join - the black wire from
'circuit power supply cable' + the
red wire coming from switch 2 + the
red wire of onward cable.
Identification of wires in onward
cable....
Black -Switched ungrounded conductor
(hot - switched)
Red - Ungrounded conductor (hot -
always on)
White - Grounded conductor (neutral)
Foreign Users:
The
colors of the wires depicted are
based on the standards and code
requirements / configuration in the
United States and Canada. If you are
viewing this site from a foreign
country, your wiring standards and
color of wires may be different but
the principal and sequence of wiring
will still remain the same.
Therefore the information in this
article may still be of use to you
regardless of what country you may
be in. Just translate the colors
used here to the color of wires used
in your country in regards to
ungrounded (hot) conductors /
grounded conductors (neutral) and
equipment grounding conductors as
well know applicable code
requirements in your country.
By: Donald Kerr
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