Electrical Terms

BTU (British Thermal Unit)

A BTU is the standard unit for measuring the quantity of heat energy such as the heat content of fuel. It is the amount of heat energy necessary to raise the temperature of one pound of water one degree Fahrenheit (3412 BTU's=1 kWh).

Kilovolt

A Unit of electrical potential equal to 1,000 volts. Abbreviated kV or KV.

Branch Circuit, Appliance

A branch circuit that supplies energy to one or more outlets to which appliances are to be connected, and that has no permanently connected lightning fixtures that are not a part of an appliance.

National Electrical Code (NEC)

A code/guideline used for the safeguarding of people and property from hazards related to the use of electricity. Compliance with this code along with proper maintenance will result in an installation essentially free from hazard. Abbreviated NEC. The NEC was first developed in 1897 as a result of the efforts of various insurance, electrical, architectural, and allied interests. It is sponsored and regularly updated by the National Fire Protection Association.

Universal Taps

A combination of six primary voltage taps consisting of four 2-1/2% FCBN and two 2-1/2: FCAN, covering 15% voltage range.

Circuit

A complete path from the energy source through conducting bodies and back to the energy source.

Ground

A conducting connection, intentional or accidental, between an electrical circuit or equipment and the earth, or some conducting body that serves in place of the earth. Other associated terms are: Grounded conductor - A system or circuit conductor that is intentionally connected to ground. This conductor has also been referred to as the neutral or common conductor. Grounding conductor - a conductor used to connect equipment or the grounded circuit of a wiring system to the grounding electrode (s). Ungrounded conductor - A current carrying conductor not connected to ground.

Ground (Wire)

A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.

Tap

A connection brought out of the winding at some point between its extremities, usually to permit changing the voltage or current ratio.

Impulse

A current surge.

Load Curve

A curve showing instantaneous demand (kVA or MVA) versus time. Curves are usually plotted for one day or one week. Integrating the load curve will provide the amount of energy consumed.

Circuit Breaker

A device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a pre-determined overcurrent without damage to itself when properly applied within its rating.

Circuit Breaker

A device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a predetermined over current without damaging itself when operated according to its rating.

Distribution Equipment

A device designed to provide electricity to multiple connections.

Reactor

A device for introducing inductive reactance into a circuit for motor starting, operating transformers in parallel, and controlling current.

GFCI (Ground Fault Circuit Interrupter)

A device intended for the protection of personnel that de-energizes a circuit or portion of a circuit when the current to ground exceeds a preset value. "Ground Fault" is the name applied to this undesired circuit condition. In dwelling units (e.g. houses, apartments), GFCI protection is currently required in bathrooms, garages, outdoors, unfinished basements, kitchens and wet bar sinks. Other specific installations and/or areas may also necessitate the need for protection

Controller

A device or group of devices that serves to govern, in some predetermined manner, the electric power delivered to the apparatus to which it is connected.

Uninterruptible Power Supply

A device that provides a constant regulated voltage output in spite of interruptions of the normal power supply. It includes filtering circuits and is usually used to feed computers or related equipment which would otherwise shutdown on brief power interruptions. Abbreviated UPS.

Capacitor

A device that stores electrical charge usually by means conducting plates or foil separated by a thin insulating layer of dielectric material. The effectiveness of the device, or its capacitance, is measured in Farads.

Wiring

A distribution network of wire that conducts electricity to receptacles, switches and appliances throughout a building/home to provide electricity where needed.

NEC (National Electrical Code)

A document produced by the National Fire Protection Association for the purpose of the practical safeguarding of persons and property from hazards arising from the use of electricity. Authorities having legal jurisdiction over electrical installations adopt the code for mandatory application ( i.e. incorporate the code into law).

Lamp

A general term for various devices for artificially producing light including commonly called items such as light bulbs and fluorescent tubes.

Equipment

A general term including materials, fittings, devices, appliances, fixtures, apparatus, and the like used as a part of, or in connection with, an electrical installation.

Neutral Grounding Resistor

A grounding device, the principal element of which is resistance, which is used to connect the neutral point of the transformer to earth.

Battery:

A group of two or more cells connected together to provide electrical current. Sometimes also used to describe a single cell which converts chemical energy to electrical current.

Transient

A high amplitude, short duration pulse superimposed on the normal voltage.

Whole-House Fan

A large fan used to ventilate your entire house. This is usually located in the highest ceiling in the house, and vents to the attic or the outside. Although whole-house fans are a good way to draw hot air from the house, you must be careful to cover and insulate them during the winter, when they often continue to draw hot air from people's houses.

Switchboard

A large single panel, frame, or assembly of panels on which are mounted, on the face or back, or both, switches, overcurrent and other protective devices, buses, and usually instruments. Switchboards are generally accessible from the rear as well as from the front and are not intended to be installed on cabinets.

Normal Duty

A lightning impulse classifying current category for distribution class arresters defined by ANSI/IEEE C62.11. A normal duty rated arrester has 5000 amperage impulse value crest (refer to heavy duty).

Continuous Load

A load where the maximum current is expected to continue for 3 hours or more.

Thermostat

A low voltage electronic switching device that monitors temperatures inside the home and turns on and off the heating or cooling system in the home.

Insulation

A material having a high resistance to the flow of electric current; insulation over underground conductor is made of either EPR or XLPE material.

Analog:

A measuring or display methodology which uses continuously varying physical parameters. In contrast, digital represents information in discrete binary form using only zeros and ones.

Outlet

A point on the wiring system at which current is taken to supply utilization equipment.

High-Tech Troubleshooting:

A procedure performed by a trained technician for the purpose of locating and identifying electrical problems within an electrical system.

Brownout:

A reduction in voltage and/or power when demand for electricity exceeds generating capacity. The term brownout is misleading because customers generally do not notice the reduction, except when it affects sensitive electronic equipment.

Generator:

A rotating machine which converts mechanical energy into electrical energy. In the automotive industry traditional terminology uses generator to refer to only those machines designed to produce dc current through brushes and a commutator (as opposed to alternator).

Fault

A short circuit in an electrical system.

Cell

A single device which converts chemical energy into electrical current. Sometimes also referred to as a battery.

American Wire Gauge (AWG)

A standard measure which represents the size of wire. The larger the number, the smaller the wire. Abbreviated AWG.

Ohm's Law

A statement of the relationship, discovered by the German scientist G. S. Ohm, between the voltage, amperage and resistance of a circuit. It states the voltage of a circuit in volts is equal to the product of the amperage in amperes and the resistance in ohms.

Transformer

A static electrical device which by electromagnetic induction transfers electrical energy from one circuit to another circuit usually with changed values of voltage and current in the process.

Conductor

A substance or body capable of transmitting electricity. Bare - A conductor having no covering or electrical insulation whatsoever. Covered - A conductor encased within material of composition or thickness that is not recognized by the NEC as electrical insulation. Insulated - A conductor encased within material of composition or thickness that is recognized by the NEC as electrical insulation.

Limit Switch

A switch that is operated by some part or motion of a power-driven machine or equipment to alter the electric circuit associated with the machine or equipment.

Switch Limit

A switch that is operated by some part or motion of a power-driven machine or equipment to alter the electric circuit associated with the machine or equipment.

Symmetric

A term used to explain the normal, rhythmic ac flow of current (transient or dc component = ); the steady state component of any current or fault current calculation.

Liquid-Filled Transformer

A transformer in which the core and coil are immersed in a liquid which acts as both a cooling and insulating medium.

Ampere

A type of electric current produced by one volt applied across a resistance of one ohm. It is also equal to the flow of one coulomb per second. Named after French physicist Andre M. Ampère 1836.

Electric Resistance Heating

A type of heating system that generates heat by passing current through a conductor, causing it to heat up. These systems usually use baseboard heaters, often with individual controls. They are inefficient and are best used as a backup to more efficient options, such as solar heating or a heat pump.

Device

A unit of an electrical system that is intended to carry but not utilize electric energy.

Device

A unit of an electrical system that is intended to carry but not utilize electricity. Receptacle - a device installed for the connection of a single contact device. Receptacles provide a means of connecting apparatus that utilize electricity to the wiring system.

Volt Ampere

A unit of apparent power equal to the mathematical product of a circuit voltage and amperes. Here, apparent power is in contrast to real power. On ac systems the voltage and current will not be in phase if reactive power is being transmitted. Usually abbreviated VA.

Kilowatt-hour

A unit of energy or work equal to one kilowatt for one hour. Abbreviated as kwh or KWH. This is the normal quantity used for metering and billing electricity customers. The price for a kwh varies from approximately 4 cents to 15 cents. At a 100% conversion efficiency, one kwh is equivalent to about 4 fluid ounces of gasoline, 3/16 pound LP, 3 cubic feet natural gas, or 1/4 pound coal.

Horsepower

A unit of power equal to 746 watts.

Watt

A unit of power equal to the rate of work represented by a current of one ampere under a pressure of one volt. Named after the Scottish engineer James Watt, 1819.

Joule

A unit of work or energy equal to one watt for one second. One kilowatt hour equals 3,600,000 Joules. Named after James P. Joule, an English physicist 1889.

Overvoltage

A voltage above the normal rated voltage or the maximum operating voltage of a device or circuit. A direct test overvoltage is a voltage above the peak of the line alternating voltage.

Series/Multiple

A winding of two similar coils that can be connected for series operation or multiple (parallel) operation.

Low Voltage:

A wiring system that provides power to some electronic devices operating on a voltage level much lower than the standard 110 volts. Such devices might be doorbells and thermostats.

AC and DC

Abbreviations for alternating current and direct current respectively. Current - a movement of electricity analogous to the flow of a stream of water. Direct Current - An electric current flowing in one direction only (i.e. current produced using a battery). Alternating Current - a periodic electric current that reverses its direction at regular intervals. Phase - the point or stage in the period to which the rotation, oscillation, or variation has advanced relative to a standard position or starting point. electrically, one of the voltage sources of an alternating current electrical system whose voltage state is measured relative to a standard point.

Vapor Barrier

Also called a vapor retarder, this is a material that retards the movement of water vapor through a building element (such as walls, floors, and ceilings) and prevents metals from corroding and insulation and structural wood from becoming damp.

Fitting

An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function.

Transformer

An apparatus for converting an alternating electrical current from a high to a low potential (voltage) or vice versa. Uses of transformers include but are not limited to the conversion of utility transmission voltage to the voltage of the premises wiring system and conversion of of voltage for use with chimes, alarm systems and low-voltage lighting. Transformers can also be used to compensate for minor variations equipment voltage requirements. Transformers only change voltage and amperage.

Alternator

An electric generator designed to produce alternating current. Usually consists of rotating parts which created the changing magnetic field to produce the alternating current.

Inverter

An electrical device which is designed to convert direct current into alternating current. This was originally done with rotating machines which produced true sine wave ac output. More recently this conversion has been performed more economically and efficiently using solid state electronics. However, except for the most expensive models, these devices usually do not produce perfect sine wave output. This sometimes can result in electromagnetic interference with other sensitive electronic devices.

Electronic Ballasts

An electronic device that regulates the voltage of fluorescent lamps. Compared to older magnetic ballasts, electronic ballasts use less electricity and are not prone to the flickering and humming effects sometimes associated with magnetic ballasts.

Transfer Switch

An electronic device that under certain conditions will disconnect from one power source and connect to another power source.

Diode

An electronic semiconductor device that predominantly allows current to flow in only one direction.

Interrupter

An element designed to interrupt specific currents under specified conditions.

Power Outlet

An enclosed assembly that may include receptacles, circuit breakers, fuseholders, fused switches, buses, and watt-hour meter mounting means; intended to supply and control power to mobile homes, recreational vehicles, park trailers, or boats; or to serve as a means for distributing power required to operate mobile or temporarily installed equipment.

Raceway

An enclosed channel of metallic or nonmetallic materials designed expressly for holding wires, cables, or bussbars. Examples are electrical metallic tubing (EMT), flexible metallic tubing and nonmetallic rigid conduit.

Cabinet

An enclosure designed either for surface mounting or flush mounting and is provided with a frame, mat, or trim in which a swinging door or doors are or can be hung.

Box

An enclosure designed to provide access to the electrical wiring system. Uses include but are not limited to provide device and lighting outlets and wiring system junction points. Specially designed boxes are required for the support of listed ceiling fans weighing less than 35 lb (15. kg). Fans exceeding this weight limit must be supported independently of the outlet box.

Annual Fuel Utilization Efficiency (AFUE)

An indication of how well a furnace converts energy into usable heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

Power Outage

An interruption of power.

Fuse

An over current protective device with a circuit opening part that is heated and broken by the passage of an over current through it.

Over current

Any current in excess of the rated current or ampacity. It may result from overload, short circuit or ground fault.

Resistor

Any device of material that limits the flow of current when voltage is applied.

Insulator:

Any material which does not allow electrons to flow through it.

Hoistway

Any shaftway, hatchway, well hole, or other vertical opening or space in which an elevator or dumbwaiter is designed to operate.

Conductor

Bare - A conductor having no covering or electrical insulation whatsoever. Covered - A conductor encased within material of composition and thickness that is NOT recognized by this Code as electrical insulation. Insulated - A conductor encased within material of composition and thickness that is recognized by this Code as electrical insulation.

Direct Current (DC)

Circuit in which the flow of electrons is in one direction only, from anode to cathode.

Switches

Circuit interruption devices used to control the flow of electricity to lights, appliances, and outlets.

Phase

Classification of an AC circuit usually single-phase, two wire or three wire; two-phase, three wire or four wire; or three-phase, three wire or four wire.

Cold-Weather Ballast

Compact fluorescent light bulbs require a ballast to regulate the voltage of the electricity that is applied to the gas inside the lamp. Below-freezing weather can adversely affect the electronic components in these ballasts, causing most compact fluorescent bulbs to appear dim in cold weather. Cold-weather ballasts compensate for this problem and keep the bulb glowing brightly, even in weather as cold as -10°F (-23°C).

Track And Accent Lighting

Condition specific lighting that meets special lighting requirements, providing variable lighting degrees of light and may distribute light in multiple directions.

Grounded

Connected to earth or to some conducting body that serves in place of the earth.

Waterproof

Constructed or protected so that exposure to the weather will not interfere with successful operation.

Watertight

Constructed so that moisture will not enter the enclosure under specified test conditions.

Rainproof

Constructed, protected, or treated so as to prevent rain from interfering with the successful operation of the apparatus under specified test conditions.

Primary Voltage Rating

Designates the input circuit voltage for which the primary winding is designed.

Metalclad

Devices in which the conducting parts are entirely enclosed in a metal casing.

Energy Saving Devices

Devices utilized within a dwelling designed to more efficiently make use of energy sources while providing heating, cooling, and light.

Live Parts

Electric conductors, buses, terminals, or components that are uninsulated or exposed and an electric shock hazard exists.

Alternating Current (AC)

Electric current which changes direction with a regular frequency. Domestic mains in the UK have a frequency of 50 Hertz.

Energizing

Electrically connected to a source of potential difference.

Motors

Electronic device used to move, switch, or adjust one or more of the systems within a dwelling.

Infrared Cameras

Energy contractors use infrared cameras to look at the heat leaking into or out of your house. The infrared camera "sees" the heat and can show "hot spots" where a lot of heat is being lost. This helps to identify the places where your home's energy efficiency can be improved.

Equipment

Equipment - A general term including material, fittings, devices, alliances, fixtures, apparatus , and similar items used as a part of, or in connection with, an electrical installation.

Listed

Equipment and/or materials included in a list published by an organization concerned with product evaluation and production of listed items. The listing states whether the item meets designated standards or is suitable for use in a specified manner. Listing organizations acceptable to jurisdiction authorities include Underwriters' Laboratories (UL) and CSA.

Labeled

Equipment or materials that a label or other identifying mark of a listing organization has been attached.

Fluorescent Lamps

Fluorescent lamps produce light by passing electricity through a gas, causing it to glow. The gas produces ultraviolet light; a phosphor coating on the inside of the lamp absorbs the ultraviolet light and produces visible light. Fluorescent lamps produce much less heat than incandescent lamps and are more energy efficient. Linear fluorescent lamps are used in long narrow fixtures designed for such lamps. Compact fluorescent light bulbs have been designed to replace incandescent light bulbs in table lamps, floodlights, and other fixtures.

Global Warming

Global warming is the gradual increase in global temperatures caused by the emission of gases that trap the sun's heat in the Earth's atmosphere. Gases that contribute to global warming include carbon dioxide, methane, nitrous oxides, (CFC's) chlorofluorocarbons, and halocarbons (the replacements for CFC's). The carbon dioxide emissions are primarily caused by the use of fossil fuels for energy.

Frequency

In alternating current, the rate at which the current changes direction. One complete cycle is a unit of 1 Hertz, named after the Physicist who researched AC (Alternating Current). The standard frequency in the US is 60 Hz.

Grid

In an electrical system, a term used to refer to the electrical utility distribution network.

Incandescent Light Bulbs

Incandescent light bulbs produce light by passing electricity through a thin filament, which becomes hot and glows brightly. Incandescent light bulbs are less energy-efficient than fluorescent lamps, because much of the electrical energy is converted to heat instead of light. The heat produced by these bulbs not only wastes energy, but can also make a building's air conditioning system work harder and consume more energy.

Series Gap

Internal gap(s) between spaced electrodes in series with the valve elements across which all or part of the impressed arrester terminal voltage appears.

Kilowatt (kW)

Kilowatt (kW): Real power delivered to a load (W x 1,000 VA).

Neutral

Neutral: The junction point of the legs in a Wye circuit.

Qualified Person

One familiar with the construction and operation of the equipment and the hazards involved.

Overload

Operation in excess of normal full-load rating or rated ampacity which could cause damage or dangerous overheating if continued for a sufficient time. A fault, such as a short circuit or ground fault, is not an overload. See "Over Current".

Overload

Operation of equipment in excess of normal, full-load rating, or of a conductor in excess of rated ampacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not an overload.

Receptacles

Power sources located throughout a building to provide electricity where needed.

Code Corrections

Procedure designed to eliminate wiring conditions that do not meet National Electrical Code requirements and safety conditions.

Ventilated

Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors.

Load Factor

Represents how efficiently the electrical system capacity is being used. The higher the load factor the higher the efficiency.

Systems Capacity

Represents the ability of a system to meet its customers' needs, or meet the electrical demand of its customers. System capacity is provided by generators, transmission lines, distribution networks and load management.

Service Cable

Service conductors made up in the form of a cable.

Load Center

Source for all power to the home. All circuits originate from the "Load Center" or "Service Panel." Circuit breakers are located within this panel.

Metal Enclosed

Surrounded by a metal case of housing, usually grounded.

Puncture

Term used when a disruptive discharge occurs through a solid dielectric. A disruptive discharge in a solid dielectric produces a permanent loss of dielectric strength; in a liquid of gaseous dielectric, the loss may be only temporary.

Loadbreak

The ability of a switching device to disconnect a load current without damage.

Energy

The capacity for, or the ability to do, mechanical work. Electrical energy is measured in kilowatt-hours for billing purposes.

Enclosure

The case or housing of an apparatus, fence, or walls that prevent persons from accidentally contacting energizing parts, or to protect the equipment from physical damage.

Branch Circuit:

The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).

Service

The conductors and equipment for delivering electric energy from the serving utility to the wiring system of the premises served.

Service

The conductors and equipment for delivering electrical energy from the supply system (e.g. the electric power utility) to the wiring system of the premises served

Ampacity

The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.

Volt

The electrical potential difference or pressure across a one ohm resistance carrying a current of one ampere. Named after Italian physicist Count Alessandro Volta 1745-1827.

Current:

The flow of electricity commonly measured in amperes.

Load

The load of a transformer is the power, in kVA or volt-amperes, supplied by the transformer. (Lagging Load) inductive type load. (Leading Load) capacitive load.

Reactive Power

The mathematical product of voltage and current consumed by reactive loads. Examples of reactive loads include capacitors and inductors. These types of loads when connected to an ac voltage source will draw current, but since the current is 90o out of phase with the applied voltage they actually consume no real power in the ideal sense.

Peak Demand

The maximum integrated demand during a time period.

Power

The rate at which work is performed or that energy is transferred. Electric power is commonly measured in watts or kilowatts. A power of 746 watts is equivalent to 1 horsepower.

Real Power

The rate at which work is performed or that energy is transferred. Electric power is commonly measured in watts or kilowatts. The term real power is often used in place of the term power alone to differentiate from reactive power. Also called active power.

Rating

The rating of an arrester - either duty cycle or MCOV rating.

Energy Efficiency Ratio (EER)

The ratio of the cooling capacity of the air conditioner, in Btu per hour, to the total electrical input in watts under test conditions specified by the Air-Conditioning and Refrigeration Institute.

Turn Ratio

The ratio of the number of turns in the high voltage winding to that in the low voltage winding

Joule's Law

The relationship between current in a wire and the thermal energy produced. In 1841an English physicist James P. Joule experimentally showed that W = I2 x R x t where I is the current in the wire in amperes, R is the resistance of the wire in Ohms, t is the length of time that the current flows in seconds, and W is the energy produced in Joules.

Ambient Temperature

The surrounding temperature of an area.

Impedance

The total effects of a circuit that oppose the flow of an AC current consisting of inductance, capacitance, and resistance. It can be quantified in the units of ohms.

Ohm

The unit of electrical resistance and impedance, abbreviated with the symbol omega, W. Resistance is the opposition offered by a substance to the passage of electrical current. Impedance is the apparent resistance in a circuit to the flow of alternating current.Kilowatt-hour - Work done at the steady rate equivalent to 1000 watts in one hour. Power utility companies base their billing upon the number of kilowatt-hours (KWH) consumed.

Hertz (Hz)

The unit of frequency (not just electricity, but also, for example, sound waves.

Ohm

The unit of measure for resistance.

Watt

The unit of power or rate of work represented by a current of one ampere under a pressure of one volt (abbreviated w or W). The English horsepower is approximately equal to 846 watts. Wattage ratings of lamps actually measure the power consumption not the illuminating capability.

Accessible

Three common uses of accessible: (wiring methods) - Capable of being removed or exposed without damaging the building structure of finish, or not permanently enclosed by such. Wires in concealed raceways are not considered accessible. (equipment) -Admitting close approach; not guarded by locked doors or other effective means. See readily accessible below. Readily Accessible - Capable of being reached quickly for operation, renewal, or inspections without the requirement of climbing over or removing obstacles or use of portable ladders, chairs, etc.

Circuit Extensions

To extend or add-on to an existing circuit to provide an additional power source.

Load Switching

Transferring the load from one source to another.

Appliance:

Utilization equipment, generally other than industrial, normally built in standardized sizes or types, that is installed or connected as a unit to perform one or more functions such as clothes washing, air conditioning, food mixing, deep frying, etc.

Smoke And Carbon Dioxide Detectors

Wall and ceiling mounted sensors located throughout the home used to alert occupants of deadly gasses and smoke inside the home.

Amp - or Ampere

the unit of intensity of electrical current (the measure of electrical flow), is abbreviated a or A.