Chapter 2.4, 2.5, 2.6 Flashcards
It is a broad category of electrical
or electronic machine or instrument
designed to perform a specific mechanical, chemical, heating or lighting function through the use of electrical energy.
UTILIZATION EQUIPMENT
Electric motors, air conditioning, refrigeration and heating units signs, industrial machinery, cranes, hoists, elevators, and escalators fit in the category of __________.
Utilization equipment
end-use piece of utilization equipment designed to perform a specific function such as cooking, cleaning, cooling, or heating.
E.g. Electric ranges, refrigerators, clothes washers and dryers, freezers, blenders,
toasters, and hair dryers.
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
a component in an electrical system that is designed to carry but not use electricity.
ELECTRICAL DEVICE
this includes components such as switches, receptacles, and relays.
ELECTRICAL DEVICE
the location in a branch circuit where electricity is used. For example, a lighting outlet is the location in a branch circuit where conductors provide power to a light fixture.
OUTLET
a male connecting device that has two or more prongs that are inserted into a receptacle to connect to an electrical circuit.
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 and Plugs
Female connecting device with slotted contacts. It is installed at an outlet or on equipment, where it is intended to easily establish an electrical connection with an inserted plug.
Receptacles
NEMA
National Electrical Manufacturing Association
Serves as a common outlet for portable lights and small appliances
5-15R
Used to connect a kitchen range or other heavy duty electrical equipment to an outlet.
14-50R
are for connection to the ungrounded conductor
BRASS -COLORED SCREWS
are for the grounded or neutral conductor, and
SILVER- COLORED SCREWS
are for the equipment grounding conductor
GREEN- COLORED SCREWS
Receptacles marked “CO/ALR” can be
connected to copper, aluminum, or copper clad aluminum conductors.
T
Those marked CU/AL were formerly allowed for use with copper or aluminum conductors, but can only be connected to copper conductors
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For office copy machines, commercial air conditioners, and other heavy equipment in commercial and industrial applications
5-30R
5.30p
For production copy machines, commercial air conditioners, and other heavy equipment in commercial andIndustrial applications
5-SOR
5-SOP
For heavy-duty appliances such as room air conditioners andportable shoptools in commerclaJ and industrial applications
6-lSR
6-1SP
For heavy-duty appliances such as room air conditioners and ovens in commercial and Industrial applteations
6-20R
6·20P
Forheavy-duty appliances such as large air conditioners andovens in commercial and Industrial applications
6-30R
6-30P
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
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.
HEAVY-DUTY SAFETY SWITCHES
These are enclosed and may be fused or unfused.
HEAVY-DUTY SAFETY SWITCHES
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
a simple on/off switch.
It opens or closes a single
ungrounded conductor in a circuit.
SINGLE-POLE, SINGLE-THROW (SPST) SWITCH
It is the most commonly used switch found in buildings, where it is typically used to control a lighting installation from a single location.
SINGLE-POLE, SINGLE-THROW (SPST) SWITCH
diverts current from one conductor path to another.
SINGLE-POLE,
DOUBLE-THROW {SPOT) SWITCH
A special type of SPOT switch is known as
a____________________, 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}.
SINGLE-POLE,
DOUBLE-THROW {SPOT) SWITCH
three-way switch {S3
- 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.
DOUBLE-POLE, SINGLE-THROW (DPST) SWITCH
switches provide control from one
or more points in a circuit
SWITCHING
configurations
used to provide control from one point by opening or closing the ungrounded
conductor in the circuit
SINGLE- POLE SINGLE THROW SWITCH
used when multiple control points are needed.
THREE-WAY (S3) &
FOUR-WAY (S4)
generally control operation of lighting installations
Single pole, single throw (S), Three way (S3) and Four way (S4) switches.
sometimes identified as SD, can be 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.
Key operated switches (SK)
deactivate a circuit after a preset time period hos 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.
Dimmers 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 7-day 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.
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 infrared and ultrasonic sensors work well in interior spaces such as classrooms and offices.
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any material that conducts electrical current.
conductors
A_____ is a common electrical conductor.
wire
_______________ are either solid or stranded
Electrical conductors
consist of smaller wire strands.
The basic reason for using a ___________ is to make the conductor flexible.
Stranded Conductors
constructed of one single piece of metal
tougher than a stranded conductor but
rigid and less flexible.
more likely to break if subjected to frequent flexing than stranded conductors.
Solid Conductors
the best electrical conductor material (other than a superconductor material)
it has the least resistance of common materials
_________ was used in the first mainframe
computer.
just like gold (excellent conductor), _________ is too costly for building installation
SILVER, silver wiring
used in building conductor (wiring)
installations as a compromise between
good conductivity and economy.
The ________ is aluminum with a thin
coating of copper that is metallurgically bonded to the core
Copper, wire core
has significant weight and cost advantages
over copper. Copper does, however,
conduct electricity better than _________, so an ______ wiring installation requires a thicker gauge.
Also, extra care in splicing and terminating
aluminum wire is important.
Aluminum
covered with insulation that provides electrical isolation and some physical protection of the conductor material.
prevents loss of power and the danger of short circuits and ground faults.
Conductor Insulation
contains more than one conductor bundled together in a factory assembly of wires.
An outer ________ encases and protects the conductors, simplifying the installation of multiple wiring.
Cable, sheathing
a wiring system composed of very thin cable with three or more conductors and special connectors and terminals.
designed to rest between
the topside of a smooth continuous subfloor and carpet squares.
Flat Conductor Cable
used in applications with voltages less than 30 V, such as wiring to doorbells, chimes, and thermostats.
generally contains No. 16 AWGorNo. 18AWG
conductors that are
bundled in a thin plastic sheathing.
Thermostat Cable
made of stranded conductors within a felxible insulated sheathing material.
They are designed for flexibility and bending
Cord
A wiring method uses knobs, tubes, and
flexible nonmetallic tubing to protect
and support single insulated
conductors
Concealed Knob and Tube Wiring
_______ generated by current flow through the conductor results in a loss of power.
FACT, Heat
This lost power is referred to as ___________ or ___________. Power loss (Ploss} in a conductor can
be computed with amperage (I} or voltage (V} and resistance (R} by the following
power loss, line loss
_________ is converted directly to heat. Power loss is equivalent to the ___________. The relationship between power and heat is 1 W 3.413 Btu/hr.
FACTS, Power loss, heat produced
themaximum current that
a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
Conductor Ampacity
Current is measured in amperes or “amps.” You must use the correct size wire for the current (load) requirement of the circuit to orevent the wire from overheatina.
JOJOWAIN
AMPACITY IS BASED ON THE FOLLOWING:
Wire thickness (thicker wires have larger cross-sectional areas and can carry more electrical current without overheating)
Type of conductor material (at a specific current and conductor size, aluminum produces more heat than copper)
Insulation and sheathing type (some insulation materials handle heat better than others)
Number of conductors bundled in the sheathing or in the proximity of one another (more conductors concentrate heat in an area)
Temperature and exposure of the conductor
(e.g., buried, in free air, in the attic, in crawl space, and so forth).
Because of __________, ________ is reduced in a closed circuit - that is, the voltage across two conductors is lower at the usage end than at the power supply end of the circuit.
FACT, power losses, voltage
Voltage drop is directly proportional to power loss
JOJOWAIN
are electrical boxes and cabinets that are made of metal or non-metallic materials that protect conductors, connections, controls, and other equipment
ENCLOSURES
they protect wiring, devices, and equipment from damage from accidental contact, wear, corrosive, atmospheric exposure, and sunlight
for faulty enclosed conductors, connections, controls, and electrical equipment, enclosures contain the arc and flaming, thereby confining damage from fire
ENCLOSURES
are metal and non metallic enclosures that hold devices such as switches or outlets and safety permit wiring connections
ELECTRICAL BOXES
boxes are in four primary shapes: square, rectangular, octagonal, or round
boxes can be joined together to accommodate multiple outlets or switches, namely; two-gang, three gangs, or four gang boxes
ELECTRICAL BOXES
special type of electrical box used to enclose conductor connections
connections are
commonly called junctions in the trade
JUNCTION BOXES (J-BOXES)
kind of junction box that allows access to a raceway for snaking conductors through the raceway
pullbox
in most boxes and enclosures, it can be easily removed to allow wiring to enter the box
KNOCKOUT
required for various single or combinations of switches, convenience outlets, blank covers, and dimmers; plastic attached with screws to the switch or receptacles
all the boxes should be finished with a cover plate
COVER PLATES
an enclosed channel such as conduit, tube, or gutter used for holding wires, cables, or bus bars
in some cases, metal raceways that are fully bonded serve to provide a path for the flow of fault current to ground
RACEWAY
a heavy galvanized steel or aluminum tube that looks like the galvanized steel pipe used for plumbing applications, except it is much smoother and is labeled with a UL Listed stamp or label
RIGID METAL CONDUIT
has threaded connections much like a pipe
can be used in contact with the earth and embedded in concrete
RIGID METAL CONDUIT
a galvanized steel or aluminum tube that has a thinner wall than rigid metal conduit
INTERMEDIATE METAL CONDUIT (IMC)
has threaded connections much like pipe or threadless connectors and couplings
can be used in contact with earth and embedded in concrete
INTERMEDIATE METAL CONDUIT (IMC)
thin-walled galvanized steel or aluminum tube in nominal diameters up to 4
cannot be threaded
ELECTRICAL METALLIC TUBING (EMT)
labeled with UL Listed stamp or label
joined with threadless compression couplings, couplings that are crimped into the tubing with a special indenting tool, or fittings that are tightened with screws
ELECTRICAL METALLIC TUBING (EMT)
a flame-retardant corrugated plastic tube that is semi flexible such that it can be bent by hand.
must be used behind fire rated finish materials
ELECTRICAL NONMETALLIC TUBING (ENT)
permitted in damped locations and can be set in concrete above ground
can also be solvent welded to rigid polyvinyl chloride (PVC) conduit
can be used in any building, but special precautions are required when used more
than three floors above grade
ELECTRICAL NONMETALLIC TUBING (ENT)
thin-walled pipe of PVC
joined with fittings that are solvent welded
RIGID NONMETALLIC CONDUIT
similar to armored cable yet, installed without cables or wiring in it; wiring must be pulled
FLEXIBLE METAL CONDUIT
similar to flexible metal conduit but covered with plastic, a watertight jacket that is sunlight resistant
unlike flexible metal conduit, the special connectors are watertight
LIQUID TIGHT FLEXIBLE METAL CONDUIT
are hollow voids in floors made of precast concrete slabs (core slabs) found in certain precast concrete buildings
CELLULAR CONCRETE FLOOR RACEWAYS
_______ must be made to avoid damage so that the internal diameter of a conduit will not be reduced
bends
bends can be made at the factory or field with a manual bender called ______-, or a hot box heater for plastic conduit
hickey
is of a standardized, factory assembled enclosure consisting of outer duct-like housing, bus bars, and insulators
busway
used in service equipment or as feeders because they are designed to carry a large amount of current
BUSWAY SYSTEMS
A type of busway system that used to deliver a large amount of power with low voltage drop
available in sizes from 600 A to several thousand amps
FEEDER BUSWAY
Another type of busway system used to
provide power tap-offs at multiple points
available in 100 A- 3000 A sizes
make power distribution flexible
PLUG-IN BUSWAY
_______ is available anywhere along the busway without necessitating the major service interruption.
Power
are only used in large commercial and industrial installations where large loads are concentrated (600 A and above), where large numbers of taps are required, or where superior fire and mechanical injury protection is desirable.
BUSWAY
can also be salvaged and moved
more easily and cost-effectively than ordinary conductors.
BUSWAY
________ or ________ are sheet metal or nonmetallic, flame-resistant plastic through that serve as housing that encloses and protects conductors
wire gutters OR wireways
These carry large conductors
WIREWAYS
access to the enclosure interior is through a hinged door or removable cover.
WIREWAY
