CHAPTER 17: Repel - charged particles with like charges

Electricity - positively and negatively charged Attract - charged particles with unlike charges
elementary particles of an atom
Electrical current - flow of electric charge
Classical Theory: Flow of Electrons through a conductor

Atoms - smallest unit of an element Conductor – less resistance to current flow.

Elementary particles - protons, neutrons, and Insulators – more resistance to the flow of
electrons electricity.

Proton - positively charged Semiconductors - materials that are neither

good conductors nor good insulators.
Electron - negatively charged
Static electricity - friction
Neutron - electrically neutral
Thermoelectricity - electricity from heat
Law of Charges - states that opposite charges
attract each other and similar charges repel Piezoelectricity - electricity from pressure
each other
Electrochemistry - electricity from a chemical
Equal number of electrons and protons - no reaction
charge
Photoelectricity - electricity from light
Fewer electrons - positively charged
Photons - small particles of light
More electrons - negatively charged
Magnetoelectricity - electricity from
Ions - charged atoms magnetism.

Orbital shells - electrons move in spherical Voltage or electromotive force (E or EMF) -

paths driving force behind current flow

Valence shell - outermost orbital shell of an Amperage or Inductive Flow (I) - rate of current
atom flow in a closed electrical system

Valence electrons - electrons contained in the Resistance - length of a conductor (wire)

valence shell
E = IR
First orbital shell - up to 2 electrons
Power - is the rate at which work is
Second shell - up to 8 accomplished; W (watts)

Third shell - up to 18 P = EI

Forth shell - up to 32 Energy - energy consumption value or amount

of work accomplished; Wh (watt-hours)
Modern Theory: Flow of Charged Particles
q = Pt
Electricity - tied to even smaller subatomic
particles that possess either a positive or 1 horsepower (hp) = 746 watts
negative electromagnetic charge.
1 watt (W) = 3.413 Btu/hr
1 kilowatt (kW) = 1000 W Alternating current (AC) - continuous reversal
of the direction of current flow
1 megawatt (MW) = 1 000 000 W
Frequency - cycles per second. It is expressed in
Closed circuit - uninterrupted path that allows a
hertz (Hz)
continuous flow of current through an electrical
circuit (turned on) 60 times every second power is positive

Open Circuit - interrupted path such as if the 60 times it is negative

switch in a circuit is opened (turned off)
120 times every second there is no voltage
Short circuit - current leaks through an
Waveform - representation of how AC varies
unintentional path
with time.
Series circuit - circuit without branching off to
Electric generator - mechanical device that
individual components
converts mechanical energy into electrical
Parallel circuit - current branches off to energy
individual components
AC generator - produces alternating current
Gustav Kirchhoff’s - in 1857, a German physicist that keeps reversing its direction of flow
established two laws known today as Kirchhoff’s
Turbine - rotary engine. Connected to the
Laws
generator and drives the rotation of the
Kirchhoff’s Voltage Law - sum of the potential armature shaft
differences (volt ages) in a complete circuit
Single-phase (1Φ) alternating current -
must be zero
distribution system refers to a system in which
Kirchhoff’s Current Law - flowing into the all the voltages of the supply vary in unison.
junction is the same as the total current leaving
Split-phase alternating current - distribution
the junction
system, which is where there are two voltage
Magnetism - force of attraction between sources.
ferromagnetic metals
Three-phase (3Φ) alternating current -
Magnet - displays the properties of magnetism distribution system consists of three separate
lines of single-phase power with each line out of
Electromagnet – produce in running current
phase by 120° (1⁄3 of a cycle)
through the wire
Polyphase alternating current - power with
Induction - current flow is induced in the
multiple phases
conductor
Transformer - electrical device that transfers an
Magnetic field - radiates out between the two
alternating current and voltage from one circuit
poles of a single magnet or between the poles
to another using the induction phenomenon.
of two magnets
Primary winding - expanding and collapsing
Direct current (DC) - current flow in one
magnetic field
direction in an electrical circuit
Secondary winding - transformer induces
voltage
Inductor - coil of wire that creates an Power demand charge - assessed an additional
electromagnetic field charge based on the highest rate

Inductive effect - current to lag behind the Maximum demand - is the user’s highest rate at
phase of the voltage—that is, peak amperage which energy is consumed in kilowatts
lags peak voltage
Demand charge - billing fee related to
Capacitor - composed of metal plates separated maximum demand.
by air or a dielectric material such as paper,
Demand limiting - accomplished by
ceramic, or mica.
disconnecting loads that are not needed during
Capacitive effect - current to lead the phase of periods of high demand.
the voltage—that is, peak voltage lags peak
Load shedding - a method by which
current
nonessential equipment and appliances are
Impedance (Z) - measure of resistance to deliberately switched off to maintain a uniform
current flow on an AC circuit. It is measure in load and thus limit demand.
ohms.
Load shifting - moves nonessential loads to
E = IZ periods of low demand.

Real power - “working power” that performs Peak shaving - energy storage and alternate
useful effort in a circuit sources of energy can also be used to reduce
demand peaks
Reactive power - power that generates the
magnetic field required for inductive devices to Time-of-use (TOU) rate - rewards the user for
operate. reducing power consumption during periods
when electrical demand is highest and a lower
Apparent power - “power available to use.”
rate for the remainder of the year.
Power factor (PF or cosϕ) - for a single-phase
Service or billing charge - covers the cost of
circuit is the ratio between real power and
metering and bill collecting activities such as
apparent power in a circuit
meter reading and preparing and mailing billing
Power factor - a number between 0 and 1 statements.
(frequently expressed as a percentage, e.g., a
Fuel adjustment charge - reflects periodic
0.7 PF 70% PF)
changes in the cost of purchasing, delivering,
PF is generally less than 1.0. handling, and storing raw fuel (e.g., coal, natural
gas) that is used to produce electricity
Energy charge - the cost of electrical energy
consumed ($energy)

CHAPTER 18: BUILDING ELECTRICAL

MATERIALS AND EQUIPMENT
Power station - industrial facility that houses
equipment to generate electrical energy.
Generator - mechanical device that converts
mechanical energy into electrical energy
Armature - a shaft with conductor windings Switchboard - large cabinet or assembly of
wrapped around an iron core, through a metal cabinets
stationary magnetic field, to produce current
flow Panelboard - one or more metal cabinets.
Serving a single-family residence
Power substations - small facilities in fenced
yards that reduce transmission voltages to safer Power distribution and lighting panelboards -
distribution levels. serving one floor of a commercial office building

Underground or overhead service entrance Load center - panelboard containing a

conductors - carry power from the transformer preassembled
through a metering device to the building’s Cabinet - sheet metal box
service disconnects
Cover - encloses and conceals the panelboard
Overhead service entrance conductors - service
drop Vertical buses - distribute power

Underground (buried) service entrance Overcurrent protection devices - protect and

conductors - service lateral feed branch circuits to outlets

Single phase service drops - 2 or 3 wires Termination buses - neutral and grounding
connections
Three phase service drops - 3 or 4 wires
Step-down transformer - less than its primary
Service entrance - components that connect voltage
the utility-supplied wiring (the service lateral or
service drop) to the service disconnect Step-up transformer - greater than its primary
voltage
Service entrance equipment - receives the
service entrance conductors Ventilated dry-type transformer - gaseous or
dry compound
Method of measuring power - metering
equipment Liquid-immersion transformer - insulating
liquid
Method of cutting off power - main disconnect
or switch gear Single-phase transformer - single primary
winding and a single secondary winding
Overcurrent protection devices - circuit
breakers or fuses Three-phase transformer - three primary and
three secondary windings
Electric meter - instrument that is used by the
utility company to measure and record Delta-connected transformer - series in the
electrical energy consumed form of a triangle, thus the name delta (Δ)

C/T devices - measure amperage through each Wye-connected transformer (Y) - connected at
ungrounded (hot) conductor a common point, called a neutral or star point

C/T cabinet - C/T metering devices are housed Overcurrent protection (OCP) device -
in an enclosure safeguards the building service

Service disconnect - switched off so that power Circuit breaker - switch that can be opened and
is disconnected to the building installation closed manually, automatically “trips off,” which
opens the circuit
Thermal-magnetic - most popular circuit Heavy-duty safety switches - heavy industry,
breaker commercial, and institutional
Fuse - strip of metal with a low melting General duty safety switches - industrial,
temperature general commercial and residential loads
Plug fuses - much like a lamp Single-pole, single-throw (SPST) switch - a
simple on/off switch
Edison-base plug fuse - similar to an ordinary
incandescent lamp base Single-pole, double-throw (SPDT) switch -
diverts current from one conductor path to
Cartridge fuses - cylindrical in shape another
Time delay fuses - handle an overload for Double-pole, single-throw (DPST) switch -
fraction of a second without blowing opens or closes two conductors in a circuit
Overcurrent rating - highest amperage; 5 A, 20 Double-pole, double-throw (DPDT) - three-
A, or 30 A pole, single-throw switches are also available
Amperes interruption current (AIC) - circuit Automatic switches - deactivate a circuit after a
breakers is 5000 A and 10 000 A for fuses preset time period has lapsed
Utilization equipment - electrical or electronic Dimmer switch (SD) - device in the electrical
machine (e.g. electric motors, air conditioning, circuit for varying power to a circuit
refrigeration elevators, and escalators)
Time clocks - can be used to control the time
Appliance - end-use piece of utilization period
equipment (e.g. refrigerators, clothes washers
and dryers, freezers, blenders, toasters, and Electronic timers - allow greater flexibility as
hair dryers) they can easily be set for 7-day cycles
Fixed appliances - permanently attached Photocell controls - sense light and open or
installations close a circuit with the presence of light
Stationary appliances - used at a specific Occupancy sensors - control a lighting
location but can be moved to another outlet
Infrared sensors - respond to the motion of an
Portable appliances - easily carried or moved infrared heat source
Electrical device - designed to carry but not use Ultrasonic sensors - emit a high-frequency
electricity sound
Outlet - location in a branch circuit where Electrical conductor - any material that
electricity is used conducts electrical current
Receptacle - female connecting device Mil - equal to 1/1000 inch
Plug - male connecting device Circular mil (cmil) - 0.001 in diameter circle
Switch - two or more electrical conductors in a Bus - sometimes called a bus bar, is an electrical
circuit conductor
Safety switches - used in building electrical Silver - best electrical conductor material
systems. Reduce the possibility of contact with
bare electrical conductors