ECM 111 chapter 13
. One of the screws is called the
"common" terminal and is usually colored black
Switching of receptacles can be done so the whole receptacle is switched on or off, or the wiring can be installed so that half a duplex receptacle is energized with the switch while the other half remains
"hot" at all time
. It is common wiring practice to switch the bottom half of the receptacle and leave the top half
"hot" at all times
On the other hand, if the top half were switched and a lamp cord plugged into it, the cord would hang down in front of the
"hot" half of the duplex receptacle and be in the way when another piece of electrical equipment needed to be plugged into that half
The traditional switch loop arrangement will require the white wire in the cable to be used as a
"hot" ungrounded conductor
. On a single-pole switch, two wires will be connected to the two terminal screws on the switch. Both of these wires are considered
"hot" ungrounded conductors
Dimmer switches should never be connected to a
"live" electrical circuit
The double-pole switch also has markings that indicate the
"load" and the "line" sides of the switch
witching of receptacles can be done so the whole receptacle is switched on or off, or the wiring can be installed so that half a duplex receptacle is energized with the switch while the other half remains "hot" at all times. This is accomplished by
"splitting" a duplex receptacle
The other two terminal screws are the same color, usually brass or bronze, and are called the
"traveler terminals."
. For those wiring situations when a switch is needed to control a 240-volt load a
, double-pole (also called two-pole) switches are used
Section 404.14(A) categorizes one switch type as an "alternating current general-use snap switch" and states that it is suitable for use only on
alternating current circuits
Switched receptacles are often found in areas such as
bedrooms, living rooms, and family rooms of homes
Usually the "line" set of terminals is colored
black
One three-way switch will have a
black "hot" feed conductor attached to it
Assuming the use of a nonmetallic sheathed cable, when the power source feed is brought to the first three-way switch in the circuit, the traveler wires that interconnect the traveler terminals of all four-way and three-way switches will be
black and red in color
The black-colored "common" terminal on a three-way switch should always have a
black insulated wire attached to it
d the "load" set of terminals is colored a
brass or bronze
a device with more than one switch type on the same strap or yoke
combination switch
Many residential lighting circuits are wired with 14 AWG conductors protected with a 15-ampere circuit breaker and will require switches with a 15-ampere, 120-volt rating. This switch rating is the most
common found in residential wiring
If you are wiring with conduit, three separate wires must be pulled into the
conduit between the two three-way switches
a switch type that raises or lowers the lamp brightness of a lighting fixture
dimmer switch
Section 404.2(B) actually says that switches must not
disconnect the grounded conductor of a circuit
a switch type used to control two separate 120-volt circuits or one 240-volt circuit from one location
double pole switch
Assuming the use of a nonmetallic sheathed cable, when the power source feed is brought to the
first three-way switch
A three-wire cable must always be installed between all
four-way and three-way switches
a switch type that, when used in conjunction with two three-way switches, will allow control of a 120-volt lighting load from more than two locations
four-way switch
Only traveler wires are connected to the
four-way switch screw terminals
Switches that are used to control lighting circuits are classified as
general use snap switches
Both single-pole and three-way dimmer switches will also have a
green insulated grounding pigtail
One of the drawbacks to using a traditional switch loop is that there will not be a
grounded circuit conductor at the switch location
However, pilot light switches and electronic devices like occupancy sensors typically need a
grounded conductor connected to them for proper operation
No switching in the
grounded conductor is allowed
Garages, attics, crawl spaces, closets, and unfinished basements are examples of areas where a
grounded conductor is not required at the switch location and a traditional switch loop can be installed
So, switch boxes installed on studs with a basement under or an attic above would qualify as areas where the
grounded conductor would not have to be installed
A common switch style for a ceiling-suspended paddle fan/light. The single-pole switch controls the
lighting fixture attached to the paddle fan, and the rotary switch provides three-speed control of the paddle fan
Another factor to consider is the number of switching locations for the
lighting load on the circuit
. Three-way switches (Figure 13-3) are used to control
lighting loads from two separate locations, such as at the top and bottom of a stairway
. An example of this requirement would be a living room that has three switch locations consisting of two three-way switches and one four-way switch. All of these switch locations are located in the
living room
ike the single-pole switch, the double-pole switch can control the load from only one
location
The rotary switch is used to control the paddle fan. It has three specific speed settings
low,medium,high
Nonmetallic sheathed cable (Type NM) and nonmetallic boxes are shown in the following single-pole switching illustrations because they are used the
most in house wiring
a device that upon detecting movement in a specific area will switch on a lighting load; once all movement stops and a short amount of time goes by the device switches off the lighting load; often used for outdoor lighting control in residential applications
motion sensor
a device that detects when a person has entered a room and switches on the room lighting; when everybody leaves a room and a short amount of time goes by the sensor device switches the room lighting off; often used for automatic control of room lighting in residential applications
occupancy sensor
Like single-pole and three-way switches, four-way switches work by having their
open or closed
The rotary switch is used to control the
paddle fan
Three-way switches must always be installed in
pairs there cannot be one
Section 404.14 states that switches must be used within their
ratings
The most common switch type used in residential wiring is a
single pole switch
a switch type used to control a 120-volt lighting load from one location
single pole switch
A dimmer switch (Figure 13-5) can be found in both a
single-pole and a three-way configuration and is used to brighten or dim a lamp or lamps in a lighting fixture
Dimmer switches are used in residential wiring applications to provide control for the brightness of the lighting in a specific area of a house. They are available in both
single-pole and three-way models
three-way switch is sometimes called a
single-pole double-throw switch (SPDT)
The NEC® and Underwriters Laboratories refer to the switches used to control lighting outlets in residential applications as
snap switches
Single-pole switches either let current flow through the
switch and to the load or do not
In addition, this section also states that if the conductors enter the
switch box through a raceway and a new grounded conductor could be installed in the raceway at a later date, a grounded conductor does not need to be installed
The speed of the paddle fan will need to be set by a
switch located on the fan itself in this switch arrangement
Ceiling-Suspended Paddle Fan/Light,The power source will feed the
switch location
Section 404.2(C) requires a grounded conductor be installed at the
switch location in bathrooms, hallways, stairways, or in any room suitable for human habitation or occupancy
a switching arrangement in which the feed is brought to the lighting outlet first and a two-wire loop is installed from the lighting outlet to the switch
switch loop
The switch on the table or floor lamp is left in the ON position, so when a switch is activated and energizes the receptacle that the
table or floor lamp is plugged into, the lamp comes on
Dimmer switches are used in residential wiring applications to provide control for the brightness of the lighting in a specific area of a house. They are available in both single-pole and three-way models. They differ from regular switches because they do not have
terminal screws on them
four-way switches (Figure 13-4) allow for control of lighting loads from
three or more locations, such as in a room with three doorways
You may remember that three-way switches have
three terminal screws on them
a switch type used to control a 120-volt lighting load from one location
three way switch
Four-way switches are used in conjunction with
three-way switches to control a lighting load from more than two different locations
Sometimes it is desired to continue an unswitched part of a circuit "downstream" of a switched lighting outlet. To accomplish this, a
three-wire cable is used between the switch location and the lighting outlet
a device that controls the flow of electricity on a circuit for a certain amount of time; used in residential applications to switch off a bathroom fan or ceiling-suspended paddle fan after a specific length of time has gone by
timer
There is no marking for the ON or OFF position of the
toggle on a three-way switch
It is very common for residential electricians to run the power source to the lighting outlet first and to then run a two-wire cable to the single-pole switching location. This is called a
traditional switch loop
Installing Four-Way Switches,All four terminal screws are called
traveler terminals
the traveler wires that interconnect the
traveler terminals of both switches will be black and red in color
Single-pole dimmers have
two black insulated conductors
Three-way switches are used to control a lighting load from
two different locations
Three-way dimmer switches typically come from the manufacturer with
two red insulated pigtails and one black insulated pigtail
Combination switch (Figure 13-6) devices consist of
two switches on one strap or yoke
On a single-pole switch, two wires will be connected to the
two terminal screws on the switch
A three-wire cable must always be installed between the
two three-way switches
Four-way switches must always be installed between
two three-way switches
For example, if you wire a switching situation that requires four switching locations for the same lighting load, you would need
two three-way switches and two four-way switches
Section 404.2(A) of the NEC® requires three- and four-way switches to be wired so that all switching is done in the
ungrounded "hot" circuit conductor
Switches are to be wired so that all switching is done in the
ungrounded circuit connector
One factor that electricians base their switch selection on is the
voltage and current rating of the circuit that the switch is being used in
When wiring a house with nonmetallic sheathed cable, a two-wire cable is available with only a
white insulated conductor and a black insulated conductor
electrical loads in a house can operate on
120 volts, 120/240 volts, or 240 volts
Type NM is available as a four-wire cable in
14/4 and 12/4 styles from some manufacturers
A double-pole switch (Figure 13-2) is used to control a
240-volt load in a residential wiring system, such as an electric water heater
Three-Way Switching Circuit This switching circuit is drawn with a metal
4 × 2⅛ inch octagon box at the lighting outlet