CHAPTER 2, UTILIZATION EQUIPMENT DEVICES Flashcards
end-use piece of utilization equipment designed to perform a specific function such as cooking, cleaning, cooling, or heating
APPLIANCE
permanently attached installations such as a built-in electric cook top or oven
FIXED APPLIANCES
situated and used at a specific location but can be moved to another outlet such as a refrigerator, clothes washer, or clothes dryer.
STATIONARY APPLIANCES
appliances that can be easily carried or moved such as a hair dryer or toaster.
PORTABLE APPLIANCES
____________is a component in an electrical system that is designed to carry but not use electricity.
electrical device
Electrical device includes components such as _________, ________, and _______.
switches, relays, receptacles
the location in a branch circuit where electricity is used.
outlet
a male connecting device that has two or more prongs
plug
typically connected to a flexible cord that is attached to a portable appliance, light, or equipment.
plug
_____________ and ________ offer a simple way to attach or detach an appliance or piece of equipment to/from an electrical outlet.
receptacles, plugs
nema
national electrical manufacturing association
_______ colored screws are for connection to the ungrounded conductor;
brass
____________ colored screws are for the grounded or neutral conductor
silver
________ colored screws are for the equipment grounding conductor.
green
Receptacles marked “CO/ALR” can be connected to copper, aluminum or _________ conductors.
copper-clad aluminum
Those marked “CU/AL” were formerly allowed for use with copper or aluminum conductors, but can only be connected to copper conductors. They are no longer deemed acceptable for use with _________ conductors.
aluminum
A ________________ is a device placed between two or more electrical conductors in a circuit to safely and intentionally open or close the circuit or to redirect the path of current in a circuit.
simple switch
Switches are rated by ________, _________, and _________,
purpose, voltage, amperage
_______________ are used in building electrical systems. They are designed to reduce the possibility of contact with BARE ELECTRICAL CONDUCTORS and have current interrupting capability.
safety switches
designed for heavy industry, commercial, and institutional applications where SAFETY, PERFORMANCE, and CONTINUITY of service are required. These are enclosed and may be fused or unfused. They are used extensively as motor circuit switches, service entrance switches, and feeder disconnects, as well as for industrial furnaces, capacitors, transformers, and welders. Ratings up to 1200 A, 600 V are available.
heavy-duty safety switches
intended for industrial, general commercial and residential loads where ECONOMY IS IMPORTANT and requirements are less stringent. They are used on lighting, heating, appliance, and intermittent motor loads. Ratings up to 600 V are available.
general duty safety switches
refers to the number of conductors the switch is opening and closing
pole
refers to the number of operations a switch can perform
throw
• It opens or closes a single ungrounded conductor in a circuit.
• It is the most commonly used switch found in buildings, where it is typically used to control a lighting installation from a single location.
SPST
• diverts current from one conductor path to another.
• A special type of SPDT switch is known as a three-way switch (S3), which allows the control of an installation from two locations (for instance, turning a light on or off from either end of a flight of stairs).
SPDT
• opens or closes two conductors in a circuit.
• It is equivalent to two SPST switches controlled by a single mechanism.
• It can be used to switch off the ungrounded and grounded conductors in a single lighting circuit that is serving a paint spray booth containing explosive vapors.
DPST
used to provide control from one point by opening or
SPST
used when multiple control points are needed.
S3 and S4 9 Three way and Four way
control from one point
SPST
control from three poibts
2 S3 and a S4
control fro four or more points
2 s3 AND 2 OR OR MORE S4
• generally control operation of lighting installations.
Single-pole, single-throw (S), Three-way (S3) and Fourway (S4) switches
• can used to adjust brightness of a lighting installation by adjusting the current flowing through the circuit.
DIMMER SWITCHES
• require a key to operate the switch. These are used where operation of a lighting installation or other piece of equipment must be further controlled by limiting operation to personnel holding a key such as in lighting in a high school gymnasium or large meeting room and equipment in a manufacturing plant.
KEY OPERATED SWITCHES
deactivate a circuit after a preset time period has lapsed.
automatic switcheS
• Available as a twist-turn device where the operator determines the operating time interval by how far the switch is twisted or as an electronic device that looks like a normal on/off switch but is designed to automatically switch off after a PRESET time.
automatic switcheS
• is a device in the electrical circuit for varying power to a circuit.
• are usually included in a lighting installation
to vary the intensity of light emitted by the Lights
dimmer switcheS
can be used to CONTROL THE TIME period that a piece of equipment or a lighting installation operates.
time clocks
• allow greater flexibility as they can easily be set for 7day cycles.
• They do require relay switching on large loads.
electronic timerS
• sense light and open or close a circuit with the presence of light.
• They can be used to control night lighting in lieu of a time clock.
• Recent advancements in photocell technology allow them to be used effectively to control illumination levels in spaces that have daylight available.
photocell controlS
control a lighting or equipment installation by sensing occupants in a space. These are usually mounted on the wall or ceiling.
occupancy sensorS
respond to the motion of an infrared heat source, such as a person or animal.
infrared sensorS
• emit a high-frequency sound that is in the range of “25” to “40” kilohertz and well above the capacity of normal human hearing.
• they do not require a direct line of sight to the occupant.
ultrasonic sensorS
Both ___________ and ____________ work well in interior spaces such as classrooms and offices.
infrared, ultrasonic sensors