Alternating Current (AC) – A flow of electrons which reverses its direction of flow at regular intervals in a conductor.

Ambient Temperature – The temperature of the surrounding medium, most commonly air, which comes into contact with a particular component.

Ammeter – An instrument for measuring the flow of electrical current in amperes. Ammeters are always connected in series with the circuit to be tested

Amperage – The measure of electrical current in amperes. 

Ampere (Amp) – A unit of measurement for Electrical Current.

Amplifier – A device of electronic components used to increase power, voltage, or current of a signal.

ANSI – Abbreviation for American National Standards Institute.

ANSI Code – A three letter system that has been devised to describe lamps of different manufacture but the same application. The letters have no relationship to lamp description, but the same letters always designate the same type of lamp. Some of the application parameters they define are wattage, base type, envelope size, and light center length.

Arc – The light caused by an electrical discharge between two electrodes in a gas such as xenon, argon, or air. The first usable arc as a practical light source was developed in 1809 by Sir Humphrey Davy.

Axial – A term used to describe a luminaire whose lamp is mounted on the same axis as its optical system.

Backlight – Illumination on a subject from behind, causing a separation of the subject from the background, often creating a fringe of light around the subject OR a luminaire that provides such illumination.

Ballast – An electrical apparatus that limits the electrical current in a particular circuit, usually a circuit containing an arc source.

Bank – A group of luminaires OR group of dimmers or dimmer modules OR a group of sliders or channels on a control console.

Bare Ends – Leads without a connector installed.

Bare Leads – See the definition for Bare Ends.

Barrel – Male turn-around, generally used for the connection of control cables.

Base – The part of a lamp to which the electrical connections are made, i.e., the part with the contacts. It is often the mechanical support and/or heat sink for the lamp OR the flat, bottom support for some luminaires.

Beam – Generally, the conoid, or in some cases, the pyramid of light emanating from a luminaire. In Photometry, the circular area of the base of a cone-shaped beam where the intensity is at least 50% of the maximum intensity. The maximum intensity is ideally located at the center of the base. It should be noted that some luminaires can be adjusted or designed such that the light emanating from them does not include the entire beam, i.e., the edge of the beam is greater than 50% of its center.

Beam Angle – The angle of the vertex of a cone shaped beam where the perimeter of the base is defined by where the intensity is 50% of the maximum intensity.

Beam Pattern – The complete shape of the beam, as defined in the general sense. It includes any realistic or abstract patterns introduced into the beam as well as any apparatus that alters the contour of the beam.

Beam Spread – See the definition for Field Angle.

Breakout – A special power cord that has one male or female multi-connector electrically connected to a plurality of female or male connectors, respectively, via separate cables or sets of sleeved wires. In most cases, each contact of the multi-connector is electrically connected to only one of all of the collective contacts on the other connectors.

Burnout – The melting of a lamp filament.

Bus – A conductor comprising a thick metal strip, usually copper, brass, or aluminum, to which other devices, such as fuses and circuit breakers, as well as a means to make electrical connections, may be attached. Buses are often used in power distribution equipment that handle large amounts of electrical current, e.g., panelboards and switchboards.

Cable –  A rope of wire used to transmit electricity or data OR to run, hook up, and/or interconnect electrical cables and the items to which the cables are connected OR a strong, flexible, wire rope made of steel, used to support pipes, battens, truss, etc., from an overhead structure.

Cable Bundle – A group of electric cables attached at various points by tape, rope, etc.

Cable Drop – An overhead electric cable or group of electric cables that extends downward for the connection of luminaires or other electrical apparatuses. The cable(s) may be connected to some type of overhead support, or directly to a piece of distribution equipment.

Cable Mount – A term used to describe a connector designed to be electrically attached to the end of a cable.

Candle (cd) – The unit of Luminous Intensity of a light source.

Candlepower (cp) – A term often used in place of Luminous Intensity.

Cap – The removable or hinged, rear cover of some luminaires that contains the lamp socket, lamp, and power cord OR see definition for Base.

Capacitor – A device which stores electrical energy. Commonly used for filtering out voltage spikes.

Carbon Arc – An arc source in which the arc is formed in air between a pair of carbon electrodes.

Card – In general, a circuit board OR see Dimmer Card or Control Card.

Circuit (ckt) – A complete electrical path leading from an electrical supply through conductors and perhaps dimmers, distribution equipment, electrical devices, electronic items, etc. to the load and returning to the source. The load is quite often a lamp.

Circuit board – A plastic or fibrous card that contains electronic components and the wiring and/or tracers that interconnect them.

Circuit Breaker – An electrical device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a predetermined over current without damage to itself.

Circuit Breaker Panel – A panelboard that houses circuit breakers.

Cold Start – A term used to describe the ignition of a cold arc lamp, i.e., a lamp that has not been electrified for a relatively long period of time.

Color Rendering Index (CRI) – CRI or Color-Rendering Index, refers to the quality of color perception that a light source provides. Scaled from 0-100, daylight is considered to be 100 CRI and the standard against which all artificial lamps are compared. LEDs have a high CRI, usually in the range of 75-95. LEDs with high CRIs produce “white” illumination.

Color Temperature – The temperature, in degrees Kelvin, of a black-body that generates light with the closest visual color match to the source being specified, i.e., a measure of the color appearance of light, not the actual temperature of the light.

Concave – A term used to describe a lens side that is inwardly and usually spherically curved.

Conduct – To carry electrical current.

Conductor – Generally, anything that will carry electrical current, but usually refers to an insulated wire.

Connector – Specifically, the name for a family of electrical wiring devices, such as plugs and receptacles, comprising one or more contacts, a means for electrically attaching a conductor to each contact, a means for electrically insulating each contact from the other, and an overall insulating material around the complete assembly such that only the contacts are exposed when the connector is properly installed to the item containing the conductors. Generally, any item used to make an electrical connection between two or more separate conductors.

Connector Box – see Plug-In Box

Connector Strip – A piece of power distribution equipment comprising an elongated metal housing, and a plurality of female flush mount connectors or female pigtail connectors for the purpose of supplying electricity to luminaires. The line side is usually hard-wired, and it gets its electrical supply from dimmers.

Console – see Control Console.

Convex – A term used to describe a lens side that is outwardly and usually spherically curved.

Cool Color – Generally, a color that is in the green-blue-violet range.

Cool Light – Light having a color temperature of approximately 3600°K to 4900°K, i.e., bright-white to blue-white.

Cord Wrap – A loop made of rope attached to a yoke for the purpose of supporting excess coils of electric cable. A round bracket provided on the rear of some luminaires for the purpose of retaining coils of electric cable when the luminaire is to be stored or transported.

Current – Movement of electricity along a conductor. Current is measured in amperes.

Current Flow – The flow or movement of electrons from atom to atom in a conductor.

Cut Sheet – Also known as data sheet or spec sheet; a paper, pamphlet or leaflet that has detailed information about a lamp, luminaire, piece of equipment, etc., usually supplied by the manufacturer.

Cycle – The change in an alternating electrical sine wave from zero to a positive peak to zero to a negative peak and back to zero.

Data Sheet –  see Cut Sheet.

Daylight – Light that has a color temperature of approximately 5500-5600°K, which has been approximated to be the color temperature of ordinary sunlight during the day under normal atmospheric conditions.

DC Volts (VDC) – A unit of measurement for Voltage Potential, specifically for direct current voltages.

Dead – Anything that is supposed to be carrying, or has the potential to carry electrical current, but isn’t.

Differentiator Circuit – A circuit that consists of resistors and capacitors designed to change a DC input to an AC output. It is used to make narrow pulse generators and to trigger digital logic circuits. When used in integrated circuits it is known as an inverter.

Diffuse – To scatter light using diffusion material OR a term used to describe a somewhat dull and/or stippled surface that is moderately reflective.

Diffusion Material – Any reflecting or transmitting media for which the reflected or transmitted light is distributed uniformly, i.e., scattered over a wide range.

Dim – To change the intensity of a luminaire. The state of a luminaire at very low intensity.

Dimmer – An apparatus used to control the intensity of a luminaire.

Diode – An electrical device that will allow current to pass through itself in one direction only.

Direct Current (DC) – An electrical current that maintains constant direction.

Direct Current Voltage – A voltage that maintains constant polarity.

Distribution – see Light Distribution.

Double Ended Lamp – A somewhat elongated lamp that has a base and contact on each end.

Down Light – Downward illumination, almost perpendicular with the floor OR a luminaire that provides such illumination.

Dress – To arrange electric cables in a neat and orderly fashion.

Driver (Power Supply) – A driver or power supply is a device that supplies electrical power to an electrical load so that it may convert the power from one form of energy to another. Power supplies obtain energy from either an AC or DC line, batteries, fuel cells, generators, or converted from a solar panel.

Drop Box – see Plug-In Box.

Edison Connector – The standard household male, parallel blade connector that may or may not have a ground pin.

Edison Lampholder – The standard household screw-type lamp socket that accepts medium screw type lamp base.

Efficacy – Efficacy refers to the ratio of light output to power consumed. It is measured in lumens per watt. LEDs generally have a high efficacy, meaning they produce high light output in relation to the amount of power they consume.

Electrical Field – The region around a charged body in which the charge has an effect.

Electrical Frequency – The cycles per second of alternating current, in Hertz. In North America, and parts of South America and South East Asia, the frequency is 60 Hz. The rest of the world operates at a frequency of 50 Hz.

Electrical Noise – A general term for an unwanted electronic disturbance in conductors or electrical or electronic equipment. This equipment can also be the cause of electrical noise.

Electrical Panel – see Panelboard.

Electrical Supply – Anything that has the potential to provide voltage and electrical current, i.e., electrical power.

Electrician – Generally, one versed in the field of electricity and its application

Electricity – The physical phenomena associated with the presence and flow of electric charge.

Electromagnetic Induction – The process by which voltage is induced in a conductor by varying the magnetic field so that lines of force cut across the conductor.

Electron – A tiny particle which rotates around the nucleus of an atom. It has a negative charge of electricity.

Electron Theory – The theory which explains the nature of electricity and the exchange of “free” electrons between atoms of a conductor. It is also used as one theory to explain direction of current flow in a circuit.

End Prong Base – A lamp base, 1/2″ deep, with two flat, parallel contacts protruding from the bottom.

Energy – Electrical energy refers to potential energy before it is delivered to the end-user/customer

Envelope – The outer glass part of a lamp.

ETL, UL, CSA & DLC – These are acronyms of four different NRTLs (Nationally Recognized Testing Labratory). CSA is a Canadian alternative. These labs test products to verify what a manufacturer claims. When certified by one, it is recognized as meeting the standards of the others. ePower Manufacturing uses Intertek, which is the ETL (Edison Testing Laboratory), and our products are also qualified products on the DLC (Design Lights Consortium).

Extended End Prong Base – A lamp base, approximately 1-1/4″ deep, with two flat, parallel contacts protruding from the bottom.

Extension – A catch-all term used to describe any item that stretches the reach of, or increase the length of something

Feed – See Electrical Supply.

Feeder Cables – A set of electric cables, usually individually insulated conductors with a high ampacity

Feeders – See Leads, short for Feeder Cables.

Female – A term applied to a connector that contains the holes and/or slots for receiving the pins, prongs, blades and/or tabs of a male connector. The female connector should always be attached to the line side of a circuit.

Filament – The wire inside an incandescent lamp envelope that glows and emits light when heated, i.e., when electricity passes through it.

Fixture – A term that is often used interchangeably with Luminaire.

Flicker – The strobing of some luminaires that cannot be visually detected because of the frequency of its output voltage, but can adversely affect light.

Flicker-Free – A term used to describe electronic ballasts that electronically alter the electrical frequency that causes flicker.

Flood Light – A luminaire consisting of a reflector, lamp, and sometimes a single lens, used to direct a large amount of light on a relatively large area.

Fluorescence – The property of certain materials to absorb radiation of certain wavelengths, usually ultraviolet, and re-emit the radiation as light.

Fluorescent Lamp – A lamp that uses fluorescence as its light source.

Flush Mount – A term used to describe anything whose upper surface, when installed, is flush with the surface to which it was installed.

Footcandle (fc) – Footcandles are the Imperial unit of measurement used to calculate adequate lighting levels of workspaces in buildings or outdoor environments. It is the illumination cast on a surface by a one-candela (the metric unit of luminous intensity) or the rough equivalent of a lit candle.

Frequency – The speed at which something pulses or cycles. An abridged version of Electrical Frequency.

Frosted – A term used to describe a lamp whose envelope has been stippled to the point of being translucent for the purpose of diffusing the light. A type of colorless diffusion material made of glass fibers or high-temperature plastic.

Fuse – A replaceable safety device for an electrical circuit. A fuse consists of a fine wire or a thin metal strip encased in glass or some fire-resistant material. When an overload occurs in the circuit, the wire or metal strip melts, breaking the circuit

Gas Light – A luminaire that uses burning gas as its light source.

Generator – An electrical supply, usually portable, that comprises a diesel or gasoline powered machine and electromagnets for the purpose of generating electricity.

Ghosting – A term used to describe a filament, lamp or luminaire that is barely glowing.

Ground – A conducting connection between an electrical circuit or electrical equipment and earth, or to some conducting item that serves in place of the earth. In most alternating current circuits, ground has a voltage potential of zero.

Ground Pin – The pin, prong, blade, or tab on some male connectors for the purpose of making a connection ground.

Kelvin (K) – Also known as Color Temperature. In the metric system, a graduated scale used to measure temperature with 0° (-273°C) being the total absence of heat (absolute zero). Each degree is the same magnitude as a degree in the centigrade scale.

Kill – To disconnect electrical current to one, some, or all luminaires, motors, or other electrical equipment.

Kilo (k) – A numerical prefix denoting 1000.

Kilovolt (kV) – 1000 volts.

Kilovolt-Ampere (kVA) – 1000 volt-amperes.

Kilowatt (kW) – 1000 watts.

Lamp – Any light source in a self contained package, comprising an envelope, filament or electrodes, base, contacts, gas, and any support structures. The source can be of the LED, incandescent, fluorescent, or arc type. Quite often this term is used interchangeably with Luminaire

Lampholder – The electrical device that supports a lamp in a luminaire, and generally contains the contacts that make the electrical connection to the contacts of the lamp base.

Leads – The electric cable(s) or sleeved, insulated wires, attached to a luminaire or piece of power distribution equipment via a strain relief, that terminate in a connector for the purpose of providing an electrical connection to the electrical supply or to another luminaire.

Lens – A transparent material, usually glass or polycarbonate, shaped to bend light rays as they pass through it.

Lens Holder – Any apparatus used to retain a lens.

Light Distribution – The way in which illumination of any color or quantity is spread over a particular background or surface.

Light Emitting Diode (LED) – A solid-state display device that emits infrared light when a forward – biased current flows through it.

Light Meter – Any apparatus used to measure various quantities of light, i.e.., color temperature, footcandles, lux, etc.

Light Source – Anything that emits light, such as an arc or a filament, or in early stage light, the flame of a burning wick or gas.

Lighting Design – The complete layout and presentation of the lighting designer.

Lighting Designer – One who plans lighting compositions, lays out light plots, directs the focusing of luminaires, and determines the various intensities of lights in a space.

Live – Having any voltage potential in reference to neutral or ground.

LM-79 & LM-80 – These are tests for solid-state lighting products administered by a Nationally Recognized Testing Labratory. LM-79 relates to general specifications such as luminous flux and power consumption. LM-80 measures light depreciation over time.

Load Rating – The maximum electrical load that something, such as wire, fuses, electrical connectors, etc., can safely accommodate. The maximum weight that something can safely accommodate.

Lumen – A unit of measurement for Luminous Flux.

Luminaire – A complete unit for the purpose of generating usable and somewhat controllable light that comprises one or more lamps, parts designed to distribute the light, parts used to position and protect the light source, and a means to connect the light source(s) to an electrical supply.

Luminance – A measure of the light, i.e.., luminous flux, per unit area leaving a surface in a particular direction. This quantity was formerly known as Brightness.

Luminous Intensity (I) – A measure of the strength of a light source in a particular direction, in Candles or Candelas. It is independent of the distance from the source.

Lux – A metric unit of measurement for Illumination, i.e.., 1 lumen per square meter.

Male – A term applied to a connector that contains the pins, prongs, blades, and/or tabs for insertion into the holes or slots of a female connector. The male connector should never be attached to the line side of a circuit.

Medium Base – A lamp base that falls in the middle range of sizes for the type of base in question, i.e.. approx. 1″ diameter for screw and prefocus type bases, approx. 7/8″ post-to-post distance for bi-post bases, approx. 3/8″ pin-to-pin distance for two-pin bases, and approx. 1/2″ prong-to-prong distance for side prong bases.

Medium Throw – A term used to describe a luminaire that has an effective intensity at a relatively moderate distance. This term is very subjective and dependent on the type of luminaire used.

Mogul Base – A lamp base that falls in the larger range of sizes for the type of base in question, i.e.., approx. 1-1/2″ diameter for screw and prefocus type bases, approx. 1-1/2″ post-to-post distance for bi-post bases, and approx. 11/16″ prong-to-prong distance for end prong and extended end prong bases.

Multi-conductor Cable – An electrical cable that generally has more than three conductors.

Multi-connector – A connector that generally has more than three contacts.

NEMA – Abbreviation for National Electrical Manufacturers’ Association.

NEMA Configuration – An alpha-numeric code applied to connectors to guarantee consistency and interchangeability among manufacturers.

Neutral – The connection point in a data or wye system that is earth grounded, or electrically connected to an item that serves in place of the earth. A term used to describe any point on a neutral conductor. An abridged version of Neutral Conductor.

Neutral Conductor – A current carrying conductor that is electrically connected to neutral.

Non-Dimming – A term used to describe a circuit that does not pass through a dimmer. A term used to describe a load that is not intended to be connected to a dimmer.

Ohm – A unit of measurement for Resistance, Reactance, or Impedance.

Ohm Meter – An apparatus that measures resistance.

Ohm’s Law – A basic electrical formula that simply states that voltage is equal to electrical current multiplied by resistance, i.e.., V=IR

Open Circuit – A circuit that has a physical break or disconnection, whether intentional or accidental, in its electrical path.

Outlet – A female connector.

Panel – An abridged version of Breaker Panel, Circuit Breaker Panel, Electrical Panel, or Panelboard.

Panelboard – A piece of power distribution equipment comprising a box-like metal enclosure with a hinged cover, accessible only from one side, to allow access to internally mounted circuit breakers, switches, and fuses.

Parabolic Reflector – A reflector designed to align light rays generally parallel to the axis formed by the point source and the center of the reflector, eventually resulting in a cylindrical-to-wide beam. The reflector has the shape of a paraboloid.

Parallel Circuit – A circuit in which the circuit components are arranged in branches so that there is a separate path to each unit along which electrical current can flow.

Patch – To make electrical connections on a patch panel, i.e.., hard patching, or, to assign dimmers to channels on a control console, i.e.., soft patching.

Patch Panel – A large, metal cabinet that comprises a plurality of female connectors electrically connected to dimmers, and a plurality of patch cords for the purpose of changing around the load(s) that are connected to the dimmer(s). Some patch panels use parallel bus bars electrically connected to dimmers, and another set of parallel bus bars mounted 90° to the first set and electrically connected to the loads, and slidable connectors that electrically connect any bus bar from one set to any bus bar from the other set.

Phase – The fraction of a cycle through which a wave has passed at any instant, measured as an angle with 360° representing one complete cycle. “Phase” is often symbolized by Ø.

Photometry – The science of measuring light and its properties.

Pigtail – The relatively short electric cable, power cord, or leads on a luminaire or piece of power distribution equipment that may or may not have a connector installed.

Pigtail Connector – A connector that is installed on a pigtail.

Pin – A thin prong used as a contact on some male connectors and lamp bases.

Pin Connector – A type of connector in which the male comprises three elongated, cylindrical shaped linear contacts, and the female comprises three linear contacts with cylindrical holes. Older versions had only two contacts due to the fact that there was no provisions for a ground connection

Plano – A term used to describe a lens side that is perfectly flat.

Plano-Convex Lens – A lens that is plano on one side and convex on the other. These lenses converge light rays passing through them.

Plug – A male connector. Potentiometer – A variable resistor used as a voltage divider.

Power (P) – Power refers to the rate at which an electric current flows through a circuit. Power is measured in Watts.

Power Distribution (PD) – A term used to describe electrical equipment that is specially designed to intake electricity and route it to an output wiring device or devices. Wire, electric cable, and other electrical such as circuit breakers, terminal blocks, connectors, etc., are some of the items employed by power distribution equipment.

Power Supply – See the definition for Electrical Supply.

Rated Lamplife – The total length of time that a lamp should operate effectively, as set by the manufacturer.

Reactor – A ballast that uses an electromagnetic component to limit current flow.

Reflector – Generally, anything that caused reflection. A metal or glass apparatus, usually curved in some manner, used in most luminaires for the purpose of directing light rays from a light source.

Regulator – A device which controls the flow of current or voltage in a circuit to a certain desired level.

Relamp – To replace a lamp in a luminaire

Safety Cable – A steel cable that has a clip on one end and a loop on the other. It is intended to be threaded through a piece of hanging equipment and around a support structure and then clipped to its loop. It then acts as a safety support should the primary support fail.

Safety Mesh – A metal wire mesh, placed at the front of a luminaire, designed to retain large pieces of broken glass should the lens break.

Safety Screen – A metal wire screen, placed at the front of an open face luminaire, designed to retain large pieces of broken glass should the lamp break.

Safety Switch – A switch that disconnects electrical current to any uninsulated conductor that a person may come in contact with internally when a housing door is opened or damaged. The switch is automatically activated by the door or some part of the door, e. g., a lens. A switch that disconnects electrical current to an apparatus if the apparatus or any part experiences an overtemp situation.

Scissor Hanger – A mounting apparatus comprising a stud connected to a scissor-like clamp designed to attach to the metal gridwork of a hung or drop ceiling.

Screw Base – A threaded, cylindrical shaped lamp base with a single contact on the bottom. The threaded part of the base holds the lamp into its socket and acts as the second contact.

Sealed Beam Lamp – A lamp with an integral light source, reflector, and lens, all of which are either sealed within, or are a part of the envelope.

Series Circuit – A circuit in which the parts are connected end to end, positive pole to negative pole, so that only one path is provided for current flow.

Series-Parallel Circuit – A circuit in which some of the circuit components are connected in series and others are connected in parallel.

Short (OR Short Circuit) – This occurs when one part of a circuit comes in contact with another part of the same circuit, diverting the flow of current from its desired path.

Short Throw – A term used to describe a luminaire that has an effective intensity at a relatively short distance. This term is very subjective and dependent on the type of luminaire used.

Shunt – A conductor joining two points in a circuit so as to form a parallel circuit through which a portion of the current may pass.

Single Ended Lamp – A lamp that has only one base and all of its contacts on the base.

Single Phase –  A term used to describe something that requires a single phase electrical supply to operate.

Slider – The mechanism on some patch panels that makes the electrical connection between two bus bars.

SO Cable – A type of hard service, oil resistant electric cable rated for extra hard usage.

Socket – Derived from “Sockett”, see the definition for Lampholder A female connector. A hollow, cylindrical shaped mounting item used to accept studs, generally equipped with a tee-handle or bolt for setting into the stud. This prevents the receiver-stud combination from unintentionally uncoupling, and can also prevent the stud from rotating within. A relay holding device that comprises terminals for making electrical connections to the socket, and contacts that make the electrical connections to the relay. A miniature hole with two internal contacts on a diode pin matrix for the insertion and electrical connection of diode pins. In general, any threaded, round opening. The part of a carbon arc luminaire that holds the carbon rods.

Solid State – A general term used to describe an electronic component that uses immobile solids, usually semiconductors, to do what moving parts, liquids or gases once did. Transistors, thyristors, and diodes are examples of solid state components. A term used to describe an apparatus that uses these components.

Spill Ring – A metal plate placed around the lamp socket base of some luminaires to prevent light leak.

Splitter – Generally, any connector that is electrically connected to two or more other connectors, all constructed as a single unit.

Stepped Lens – A lens consisting of tiered, concentric rings on one side that are segments of the flat portion of a plano-convex lens. The other side is convex. It controls the light similar in manner as a plano-convex lens.

Stippled – A term used to describe a surface that is dimpled or covered with small indentations or bumps.

Strobe – To cause an intense light source to turn on and off repeatedly at a relatively fast rate. This is usually done in an area devoid of all other illumination to create a flickering, slow motion effect. An abridged version of Strobe Light. usually using an arc lamp as its light source.

Surface Mount – A term used to describe anything whose bottom surface, when installed, is flush with the surface to which it was installed. This term is used to describe certain types of connectors, lamp sockets, plug-in boxes, and gridiron junction boxes.

Surge – An instantaneous and usually brief increase in voltage or electrical current in a circuit. This can sometimes be detrimental to the integrity of a signal or to electronic equipment.

Switch – A device which opens or closes electrical pathways in an electrical circuit.

Swivel Yoke – A semi-circular yoke with a slot running centrally though most of its length to allow for the mounting of luminaires at various angles.

Three Phase – A term for an alternating current electrical supply that has three hot legs, with each leg at a phase that is 120° apart from the other, with or without a neutral leg. A term used to describe something that requires a three phase electrical supply to operate.

Throw – To direct the light emanating from a luminaire in a particular direction. An abridged version of Throw Distance.

Throw Distance – The effective distance between a luminaire and the area or subject to be illuminated.

Tie In – To connect the line side leads of power distribution equipment, dimmer racks, etc., to the primary electrical supply for a location, such as a company switch, circuit breaker panel, or other piece of power distribution. This is generally done with feeder cables.

Tilt – To rotate up and down around a horizontal axis.

Transformers – A device made of two coil windings that transfers voltage from one coil to the next through electromagnetic induction. Depending upon the number of windings per coil, a transformer can be designed to step – up or step – down its output voltage from its input voltage. Transformers can only function with alternating current (AC).

Transient Voltage Surge Suppressor (TVSS) – A device which protects the engine controller electronics against high energy voltage transients such as alternator load dumps

Transistor – A device constructed of semi – conductors that is used in circuits to control a larger current by using a smaller current for operation. Its function is the same as a relay.

Transmission – The ability of light to penetrate through something.

Transmission Factor – The ability of a medium to allow for the transmission of light, expressed as a percentage.

Trim – To finely adjust the voltage output of some electronic dimmer at the lowest control setting.

Twist-Lock Connector – A commonly used type of locking blade connector that requires a twisting action to lock the mating connectors together, manufactured by Harvey Hubbel, Inc. The name “Twist-Lock” is trademarked.

Underwriters’ Laboratories, Inc. (UL) –  An independent, not-for-profit organization testing for public safety. This organization Lists and Labels products and materials and Recognizes parts, components, and materials, and is acceptable to most jurisdictional authorities, e. g., electrical inspectors, fire marshals, insurance underwriters, and governmental agencies.

Volt – A unit of electrical pressure (or electromotive force) which causes current to flow in a circuit. One volt is the amount of pressure required to cause one ampere of current to flow against one ohm of resistance.

Voltage Potential (V) – Often considered to be the force of electrons moving from one point to another. Technically not a force at all, but the potential for electrons to move from one point to another, as measured in volts

Voltage Regulator – A device that controls the strength of a magnetic field produced by a generator or alternator. It prevents the battery from being over or undercharged during high – or low – speed operation of the generator or alternator.

Voltmeter – An instrument for measuring the force in volts of an electrical current. This is the difference of potential (voltage) between different points in an electrical circuit. Voltmeters are connected across (parallel to) the points where voltage is to be measured.

Warm Color – Generally, a color that is in the yellow-orange-red range.

Watt (W) – A unit of measurement for heat or Electrical Power.

Wattage (W) – The measure of electrical power in watts.

Wavelength – The distance, measured in the direction of propagation, of a repetitive electromagnetic wave between two successive points.

Yoke – A sturdy, U-shaped metal bracket that attaches to opposite sides of a luminaire, or, video and film industry reflectors, butterflies, etc., such that it allows either to tilt freely. A locking mechanism is provided to prevent slippage when the desired position has been achieved. Also provided at the center of the yoke is a hole, stud, or receiver for mounting the yoke.