A

• AFCI: Arc Fault Circuit Interrupter
• Alloy: A mixture of two or more metals combined together
• Alternating Current: Current which changes its direction and amplitude 50 or 60 times per second
• Ambient Temperature: Temperature surrounding conductors
• Ammeter: Measures current
• Ampacity: The maximum current a cable or device can handle
• Ampere: Unit of electrical current
• ANSI: American National Standard Institute
• Anode: Positive terminal of a battery
• Apparent Power: Measured in KVA
• Atom: The smallest unit of an element that retains the property of that element
• AutoCAD: Computer-aided drawing or design
• Auto-Transformer: Transformer with one winding and a number of tappings
• AWG: American Wire Gauge

B

• Back EMF: Counter electromotive force
• Battery: Two or more cells connected together; can be connected in series, parallel, or series-parallel
• Binary Numbers: A system where numbers and values are expressed in 0 and 1
• Blue Print: Large format drawings with a blue background
• Bonding Jumper: Bond from neutral to earth lug
• BTU: British Thermal Unit
• Buck and Boost Transformer: Used to step up or step-down voltage incrementally
• Bus-Bars: Solid copper or aluminum conductors used in switch gears
• Byte: A unit of memory size

C

• Cable: Composite material with two or more insulated conductors covered with an outer sheath
• Candela: Unit of luminous intensity
• Capacitive Reactance: Opposition to capacitance in an AC circuit
• Capacitor: Device which stores electrical charge
• Cathode: Negative terminal of a battery
• Celsius: Measurement of temperature
• Circuit: Arrangement of conductors for carrying electric current to the load of that circuit; consists of conductors, controlling device, load, and source
• Circuit Breaker: A device to open a circuit under normal and abnormal conditions; can be operated manually and can operate when there is a fault in the circuit
• Circular Mills of Conductors: Measure the size of conductors
• Closed Circuit: Circuit which is closed and allows current to flow
• Coil: Wire wound in a coil to produce electromagnetism
• Colour Code: Standard colors for electrical conductors (single-phase: brown for phase, blue for neutral, green for earth; three-phase: brown, grey, blue, black/neutral, green)
• Compound: A substance formed when two or more elements are chemically combined
• Conductor: Material which offers low resistance to electrical current
• Conduit or Raceway: Tubing (PVC or metal) for accommodating electrical wires/conductors
• Control Circuit: Controls the operation of a power circuit to effect operation as per the design of the circuit
• Coulomb: Quantity of electrons
• C.S.A: Cross-sectional Area
• CT: Current Transformer
• Cycle: Passage of an AC waveform

D

• DC Motors: Series motor, shunt motor, and compound motors
• Diode: Electronic device which allows current in one direction
• Direct Current: Current which flows in one straight direction
• Distribution Transformer: Reduces voltage for residential/commercial use
• Diversity Factor: The ratio of the sum of individual maximum demands to the total maximum demand of the system
• DOL: Direct On-Line starters for motors
• Down Conductor: Conductor from roof connected to earth rod
• Drip Loop: Positioning of conductors at pot head to prevent water from entering conduit
• Duct: Raceway run underground to accommodate conductors/cables

E

• Earth Fault: A fault caused by accidental contact to ground
• Earth or Ground Conductor: Bonds metal boxes and carries fault current to open circuit
• Earth Rod/Ground Rod: Conductive bar or rod used to make direct contact with ground/earth, usually copper or an alloy
• Eddy Current: Circular electrical currents induced within a conductor by a changing magnetic field
• Efficiency: Input divided by output
• Electrical Code: Safety guidelines and standards in place for electrical work
• Electrical Conduits: Tubing (PVC or metal) for accommodating electrical wires/conductors
• Electrical Diagrams: Line diagrams, wiring diagrams, and block diagrams
• Electricity Act 2015: The law governing the electrical and energy sector
• Electromotive Force (EMF): Measured in volts
• Electron: Negatively charged sub-atomic particle of an atom
• Element: A pure substance composed of only one type of atom
• Equipment Grounded Conductor: Green conductor used to bond all metallic parts in an installation
• Excitation Current: Small current drawn through primary winding when energized, even with no load

F

• Farad: Unit of capacitance
• Faraday’s Law: When a magnetic field moves relative to a conductor or vice versa, a voltage is induced in the conductor
• Fahrenheit: Measurement of temperature
• Feeder or Service Wire: Leads from pot head to main breaker
• Fire Alarm Circuits/System: Systems designed for fire detection and alerting
• Fleming’s Left Hand Rule: Determines direction of current flow in motors
• Fleming’s Right Hand Rule: Determines direction of current flow in generators
• Float Switch: Operates by liquid
• Floor Plan: Drawing showing the outline of electrical fixtures in an installation
• Fossil Fuel: Carbon-rich materials formed naturally from remains of plants and animals over many years, including coal, oil, and natural gas
• Full Wave Rectifier: Uses four diodes
• Fuse: A device with an element that melts when current exceeds its rating

G

• Generator: Converts mechanical energy into electrical energy; in AC, it is an alternator
• Germanium: Chemical element used in electronics as a semiconductor
• GFCI: Ground Fault Circuit Interrupter
• Giga: 1,000,000,000
• Grid Tie: Solar system connected to utility power
• Grounded Conductor: Neutral conductor

H

• Half Wave Rectifier: Uses two diodes
• Henry: Unit of inductance
• Hertz: Unit of frequency
• High Leg/190 Volts: High leg on a three-phase delta system
• High Voltage: Voltage level above a certain threshold (specific range varies by standard)
• Hybrid: Type of renewable energy system combining multiple sources

I

• IC: Integrated circuit with various electronic components
• IEC: International Electrotechnical Commission
• IEEE: Institute of Electrical and Electronics Engineers
• IGBT: Insulated Gate Bipolar Transistor
• Impedance: Total opposition to the flow of electric current
• Incandescent Lamp: Glows from intense heat
• Inductive Reactance: Opposition to inductance in an AC circuit
• Inverter: Converts DC power to AC power
• Ion: Atom or molecule with a net electrical charge
• Isolator/Disconnect Switch: Electrical device to open and close power to an appliance for servicing and emergency situations
• Isotope: A substance formed when two or more chemical elements are combined
• IT: Information Technology

J

• Joule: Unit of electrical energy
• JS 316 Jamaica Standard Electrical Code: Electrical standards specific to Jamaica

K

• Kilo: 1,000
• Kilowatt/Hour Meter: Measures power in kilowatt-hours
• Kirchhoff’s Current Law: The current entering any junction is equal to the current leaving that junction
• Kirchhoff’s Voltage Law: The total voltage applied to any circuit path is equal to the sum of voltage drops

L

• Ladder Diagrams: Diagrams with a ladder configuration used to interpret control circuits
• Lamp: Electrical bulb or tube that emits light
• LED: Light Emitting Diode
• Lenz’s Law: An induced electric current flows in a direction such that the current opposes the change that induced it
• Licensed Electrical Inspector: Person licensed to carry out electrical inspections as stated by the Electricity Act 2015
• Lightning Arrestor: Diverts lightning strikes to ground
• Limit Switch: Operates by mechanical action
• Line: Incoming side of power to an electrical device
• Line Voltage: Voltage measured between phases
• Load: Outgoing side of power from an electrical device
• Load Centre/Distribution Board: Residential panel board; accommodates breakers and branch circuit conductors
• Lock Rotor Current: The highest current of a motor when it is starting
• LOTO: Lock Out Tag Out
• Low Voltage: Voltage level below a certain threshold (specific range varies by standard)

M

• Magnet: Has two poles, north and south; like poles repel, unlike poles attract
• Main Component of Air Condition System: Compressor, condenser, evaporator, and metering device
• Matter: Anything that has weight and occupies space
• MCC: Motor Control Centre
• Medium Voltage: Voltage level between low and high voltage (specific range varies by standard)
• Mega: 1,000,000
• Meghometer: Meter used to measure insulation resistance
• Meter Socket: Device that accommodates a utility meter
• Micro: One over a million
• Milli: One over a thousand
• Miniature Circuit Breaker: Small-size circuit breakers used on DIN rails
• Modem: Converts signals from digital to analog and back to analog
• Molded Case Circuit Breaker: A type of circuit breaker
• Molecule: A group of two or more atoms held together by chemical bonds
• MOSFET: Metal Oxide Semiconductor Field Effect Transistor
• Motor: Converts electrical power to mechanical energy
• Motor AC or DC: Converts electrical energy into mechanical energy
• Motor Speed: Affected by frequency and number of poles
• MPVD: Maximum Permissible Voltage Drop
• Multi-meter: Measures current, voltage, resistance, and temperature

N

• Nano: One over a billion (billionth)
• National Electrical Code (NEC): Safety standards for electrical work
• NEMA: National Electrical Manufacturers Association
• Net Billing: Selling power to a utility company
• Neutral Wire: Return or negative wire in a circuit
• Neutron: Sub-atomic particle found in the nucleus of an atom
• Newton: Measurement of force
• NO: Normally Open contacts
• Nominal Voltage: Standard or reference voltage level assigned to an electrical system by a utility company

O

• Off Delay Timer: Used in control circuits
• Ohm: Unit of electrical resistance
• Ohmmeter: Measures resistance
• Ohms Law: Current in a circuit is directly proportional to voltage and inversely proportional to resistance at a constant temperature
• On Delay Timer: Used in control circuits
• Open Circuit: Circuit that is open or broken; no current will flow
• OSHA: Occupational Safety and Health Administration

P

• Panel Board: Electrical device that accommodates breakers for circuits
• Parallel Circuit: Circuit that offers more than one path for current to flow
• Periodic Table: An ordered arrangement of the chemical elements into rows and columns
• Phase Convertor: Used to convert single-phase power into three-phase power
• Phase Failure Relay: Protects three-phase motors
• Phase Motor: Motor with three windings on its stator
• Phase Voltage: Voltage measured between phase and neutral/earth
• Phase/Live Wire: Phase or positive conductor
• Pico: One over a trillion (trillionth)
• Pie: Equals 3.141
• PLC: Programmable Logic Controller
• Pot Head/Weather Head: Covering at the termination of utility and service conductors
• Power: Energy used to do work
• Power Circuit: Supplies power to equipment and appliances
• Power Factor: Ratio of true power to apparent power
• PPE: Personal Protective Equipment
• Pressure Switch: Operates by pressure from fluid or air
• Proton: Positively charged sub-atomic particle of an atom
• PSI: Pound Per Square Inch
• PT: Potential Transformer
• PV System: Photovoltaic system
• PVC: Polyvinyl Chloride
• Pythagorean Theorem: A² + B² = C²; used to calculate the missing side of a right-angle triangle

R

• RAM: Random Access Memory
• Reactive Power: Measured in KVAR
• Rectangle: Polygon with four sides
• Reduce Voltage Starter: Reduces voltage to let a motor draw less current when starting
• Reference Point to Ground: Zero volts
• Registered Electrician: Person registered by the GER under the Electricity Act
• Relay: An electrical switch operated by magnetism
• Renewable Energy: Energy derived from natural, self-replenishing sources that will not run out
• Resistor: Device used to limit the flow of current
• Resistor Color Code: Used to specify the rating of a resistor
• Resistivity: Specific resistance of a material
• RMS: Root Mean Square
• ROM: Read Only Memory
• RPM: Revolutions Per Minute

S

• Schottky Diode: A diode with low forward voltage drop and fast switching
• SCR: Silicon Controlled Rectifier/Thyristor, a solid-state electronic device
• Semiconductor: A material that is neither a good conductor nor a good insulator
• Series Circuit: Circuit that offers one path for current to flow
• Short Circuit: A fault current with little or no resistance
• Silicon: Chemical element used as a semiconductor
• Single Phase: Three-wire or two-wire 220/110 volts or 110 volts two-wire
• Single Phase Meter Socket: Four jaws
• Single Phase Motor: Motor with a starting winding and running winding
• Slip Rings on Motors: Used to transfer power to the rotor
• Slip Speed of Motor: Difference between synchronous speed and rotor speed
• Socket Outlet or Receptacle: In wall or surface; plug is used for connecting appliances
• Soft Starters: Electronic starters used to start motors
• Solar Panel: Converts photons into electricity
• Solenoid: An electromagnetic device with a plunger that operates by magnetism
• Space Factor: The amount of usable space in an enclosure
• Square Root of #2: 1.414
• Square Root of #3: 1.732
• Stand Alone: Type of renewable energy system not connected to the grid
• Star/Delta Starters: Used to start motors with reduced voltage
• Starter: A contactor with a set of overload contacts
• Static Electricity: Electrons that remain on a surface
• SWA: Steel Wire Armoured earth
• Switch: A device to open and close a circuit

T

• Tachometer: Measures RPM
• Tera: 1,000,000,000,000
• Thermostat: Operates by temperature
• Three Phase: Three wires connected in delta form or four-wire star/wye with neutral
• Three Phase Meter Socket: Seven jaws
• Three States of Matter: Solid, liquid, and gas
• Three Wire Control of Motor Starters: Has an auxiliary contact
• Three-Way Switch: Switch with three terminals
• Torque: Twisting force or rotation
• Transfer of Heat: By conduction, radiation, convection
• Transfer Switch: Switches load from one source to another
• Transformer: A static electrical device that steps up or steps down voltage
• Transformer Taps: Used to adjust voltages on transformers
• Transistor: Device used to switch current and amplify signals in a circuit
• Transmission Transformer: Transmits high voltage
• Triangle: Polygon with three sides
• Trunking: Electrical rectangular container to accommodate conductors; can be metal or PVC
• TVSS: Transient Voltage Surge Suppressor
• Twisted Wire: Triplex or quad aluminum conductors for outdoor purposes
• Two Types of Transistors: PNP and NPN
• Two Wire Controls: Has two contacts for on and off operation

U

• UL: Underwriters Laboratory
• Ungrounded Conductor: Phase, hot, or live conductor
• Universal Motors: Operate on AC and DC power
• UPS: Uninterruptible Power Supply

V

• Valence Electron: Electron in the outer shell of an atom
• Vector: Mathematical object with both magnitude and direction
• Volt: Unit of voltage
• Voltage Drop: Voltage lost due to resistance
• Voltmeter: Measures voltage
• VOM: Voltage Ohm Millimeter

W

• Watt: Unit of electrical power
• Waveform: The shape of an electrical signal

X

• XLPE Cable: Cross-Linked Polyethylene cable

Z

• Zener Diode: Diode that can conduct current in the opposite direction when a specific voltage is reached