WHILE EXTREME CARE HAS BEEN IMPLEMENTED IN THE PREPARATION OF THIS
SELF-HELP DOCUMENT, THE AWHILE 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 3 wire cable that is routed between switch box 1 and switch
box 2 - these wire cables comes with a black / red / white wire
plus the bare equipment grounding wire.
2. A 2 wire cable that is routed between switch box 2 and the
fixture box - this wire cable comes with a black / white wire
plus the bare equipment grounding wire.
3. A circuit power supply source wire cable that is feed to the
switch 1 box.
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...
One cable entering this box coming from switch 2.
* a) connect the white wire to the grounded conductor (neutral) of
fixture - if screw type connections then connect to the silver color
screw.
* b) connect the black wire to the switched ungrounded conductor
(hot) of fixture - if screw type connections then connect to the
brass color screw.
* c) please see under important notes in regards to the equipment
grounding conductor (bare wire).
At switch 1 box...
Two cables entering this box, one is the circuit power supply cable,
one cable coming from switch 2.
* a) using an insulated wire nut connect / join the white wire
coming from the 'circuit power supply cable' + the white wire coming
from switch 2.
* b) connect the black wire coming from the 'circuit power supply
cable to the common screw of switch 1.
* c) connect the red wire coming from switch 2 to the one of the
remaining main screws of switch 1.
* d) connect the black wire coming from switch 2 to the last
remaining main screw of switch 1.
*e) please see under important notes in regards to the equipment
grounding conductor (bare wire).
At switch 2 box...
Two cables entering this box, one cable coming from switch 1 and one
cable coming from the fixture.
* a) connect the black wire coming from fixture to the common screw
of switch 2.
* b) using an insulated wire nut connect / join the white wire
coming from switch 1 + the white wire coming from fixture.
* c) connect the red wire coming from switch 1 to one of the
remaining main screws of switch 2.
* d) connect the black wire coming from switch one to the last
remaining main screw of 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 switched 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 and switch 2 has 3 wires 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 switch itself 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 the 2 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 screw.
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....
Only always on power is available from the switch 1 location.
Switch 2 only has onward switched power available.
Switch 1 options...
Onward Always On Circuit
Power...
(showing bellow the switch 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 switch
electrical box.
Connection Instructions for
onward cable (switched)
* a) Using an insulated wire nut, attach / join - the white wire
of onward cable + the white wire coming from fixture + the white
wire coming from switch 1.
* b) Using an insulated wire nut, attach / join - the black wire
of onward cable + the black wire connected to common screw of
switch 2 + the black wire coming from fixture.
Identification of wires in
onward cable....
Black - Switched ungrounded conductor (hot - switched)
White - Grounded conductor (neutral)
***********
From the fixture location...
At the fixture location only switched onward power is available.
(example more than one light fixture controlled by the same 3
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, attach / join - the white wire
of onward cable + the white wire connected to the grounded
conductor (neutral) of fixture + the white wire coming from
switch 2.
* b) Using an insulated wire nut, attach / join - the black wire
of onward cable + the black wire coming from switch 2 + the
black wire connected to the switched ungrounded conductor (hot)
of fixture.
Identification of wires in
onward cable....
Black - Switched ungrounded conductor (hot - switched)
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
