Acid Rain:
Rain that has become acidic due to the emission of sulfur dioxide and nitrogen oxides.

Active Power:
See Real Power.

Air Leakage Rating:
The air leakage rating is a measure of how much air leaks through the crack between the window sash and frame. The rating reflects the leakage from a window exposed to a 25-mile-per-hour wind, and is measured in cubic feet per minute per linear foot of sash crack.

Alternating Current (AC):
Electric current which changes direction with a regular frequency. Domestic mains in the UK have a frequency of 50 Hertz.

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

Ambient Temperature:
The surrounding temperature of an area.

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

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

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.

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.

Annual Fuel Utilization Efficiency (AFUE):
An indication of how well a furnace converts energy into texasble heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

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.

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.

Blower Doors:
Energy contractors use blower doors to see how much air leaks through windows, doors, and other places in your house. The blower door is a large board that blocks the front door of your house. A powerful fan installed in the door draws the air out of your house and causes a strong draft inside where ever the air is leaking in. This can help the contractor locate the air leaks, and gives a good overall indication of how “leaky” your house is.

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

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.

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.

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).

A structure that stands alone or that is cut off from adjoining structures by fire walls with all openings therein protected by approves fire doors.

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.

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.

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

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

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

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).

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

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.

The flow of electricity commonly measured in amperes.

A logarithmic measure of the ratio of two quantities. Abbreviated dB. For electrical power, 1 dB = 10 x log10 P1/P2. For electric voltage or current, 1 dB = 20 x log10 E1/E2.

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

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

Direct Current (DC):
Circuit in which the flow of electrons is in one direction only, from anode to cathode.

Distribution Equipment:
A device designed to provide electricity to multiple connections.

One or more rooms for the use of one or more persons as a housekeeping unit with space for eating, living, and sleeping, and permanent provisions for cooking and sanitation.

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.

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.

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

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.

Electrically connected to a source of potential difference.

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

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.

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

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.

A short circuit in an electrical system.

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.

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.

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.

A building or portion of a building which one or more self-propelled vehicles carrying volatile flammable liquid for fuel or power are kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes.

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).

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.

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

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.

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

A heat source (gas or electric) used to adjust the temperature inside a dwelling from a cold to a warm condition.

Heavy Duty:
A lightning impulse classifying current category for distribution class arresters defined by ANSI/IEEE C62.11. A heavy duty rated arrester has a 10,000 amperage impulse value crest (refer to normal duty).

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

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

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

A unit of power equal to 746 watts.

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.

A current surge.

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.

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.

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

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

An element designed to interrupt specific currents under specified conditions.

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.

An Ion is a positively or negatively charged atom or molecule.

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.

Joule’s Law:
Defines 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.

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

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

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.

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.

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.

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

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.

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

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.

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.

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

Load Switching:
Transferring the load from one source to another.

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.

Metal Enclosed:
Surrounded by a metal case of housing, usually grounded.

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

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

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.

The junction point of the legs in a Wye circuit.

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.

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).

The unit of measure for resistance.

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

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.

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.

Peak Demand:
The maximum integrated demand during a time period.

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.

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.

Power Outage:
An interruption of power.

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.

Primary Voltage Rating:
Designates the input circuit voltage for which the primary winding is designed.

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.

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

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

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

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.

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

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.

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

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

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

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.

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

Service Cable:
Service conductors made up in the form of a cable.

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.

Storm Windows:
An extra pane of glass or plastic added to a window to reduce air infiltration and boost the insulation value of a window. If you are considering adding storm windows, you should compare the costs to installing new energy-efficient windows.

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.

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

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.

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.

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.

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

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.

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.

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

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.

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

Turn Ratio:
The ratio of the number of turns in the high voltage winding to that in the low voltage winding.

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.

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.

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.

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

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.

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.

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

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

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.

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

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.