Glossary of Terms

So, here is a glossary of lighting terms to help with your knowledge base.

  • Accent Lighting

    The use of lighting to accent or highlight  objects such as artwork or plants. Also,

  • Ampere or also known as Amp

    A unit expressing the rate of flow of electric current.  And,

  • A-Line Lamp – like your common lamp bulb

    A type of incandescent lamp that is mostly used for indoor residential lighting needs.  Plus,

  • Ambient Lighting

    General lighting that lights up an entire space.  Also,

  • Average Rated Life

    An average rating, in hours, when 50% of a large group of lamps have failed.  And,

  • Ballast – A device used with an electric discharge lamp

     Used to obtain the needed circuit conditions for starting and operating. Plus,

Ballasts have two functions:  For instance,

1) start the lamp.

2) control operation of the lamp once it has started.

  • Candela or Candlepower

    The unit of measure indicating the luminous intensity of a light source in a specific direction. Also,

  • Candlepower distribution

    Each lamp or lamp/luminaire has a unique set of candlepower distributions that indicate how light will be spread.  Plus,

  • Color rendering index (CRI)

    (CRI) measures the effect a light source has on the perceived color of objects and surfaces.  Also,

  • Color or Kelvin temperature 

    Indicates whether a lamp has a warm, mid-range or cool color appearance.  In addition,

  • Compact fluorescent lamps (CFL)

    Lamps that employ small diameter tubes that are bent so they begin and end in a ceramic base.  Plus,

  • Cool White Light

    Cool White is the least expensive and most widely used fluorescent lamp color in lighting today.   Also,

  • Daylight Light

    The bluish white appearance of this lamp is similar to natural daylight toward the later afternoon.  And,

  • Dimmer

    A device in an electrical circuit used for varying the brightness of lamps in a lighting installation. And,

  • Downlight or Recessed Can

    A small light fixture recessed into the ceiling that concentrates the light in a downward direction.  Also,

  • Economic Life

     The number of hours a group of lamps will burn before it is advised to group relamp.  Plus,

  • Efficacy

    The rate at which a lamp is able to convert power (watts) into light (lumens), represented in lumens per watt. Also,

  • Electronic ballasts

    The ballast starts the lamp, then limits its operating current and provides power factor correction.  In addition,

  • Emergency Lighting

    Lighting used when the normal lighting fails.  Also,

  • Energy

    A measure of work done by an electrical system over a given period of time, often expressed in kilowatt-hours (kWh).  And,

  • Filament

    A tungsten wire positioned inside a lamp bulb to generate radiation in the visible light ranges when heated.   Also,

  • Floodlight

    A lamp whose beam pattern provides a wide field of light.  And,

  • Fluorescent lamp

    A lamp that uses an electric discharge through low-pressure mercury vapor to produce ultra-violet (UV) energy.  Also,

  • Footcandle (fc)

    A unit of illuminance equal to 1 lumen per square foot.  Plus,

  • Frost

    The glass of the lamp has a slightly opaque white appearance used to soften the light by dispersing it more evenly.  And,

  • Full Spectrum

    A bulb/lamp that reproduces the full color spectrum of natural outdoor light.  Also,

  • Glare

    Excessive brightness that may be caused by either direct or indirect viewing of a light source.  And,

  • Grounding

    The grounding helps assure safety and proper lamp starting.  Also,

  • Halogen lamps

    High pressure lamps containing halogen gases which allow the filaments to operate at higher temperatures and higher efficacies.  Also,

  • High-intensity discharge (HID) lamps

    In HID lamps, an arc passing between two cathodes in a pressurized tube cause various metallic additives to vaporize and release large amounts of light. Also,

  • Illuminance

    Light arriving at a surface, expressed in lumens per unit area; And,

  • Incandescent lamps

    A light source that generates light utilizing a thin filament wire (usually tungsten) heated to white heat by an electric current passing through it inside a vacuum or gas-filled bulb.  Plus,

  • Initial Lumens

    The measure of the amount of light a lamp produces after it has been operating 100 hours.  And,

  • Instant start (IS) 

    Instant start  is the most energy efficient starting method for fluorescent lamp ballasting.  And,

  • Lamp

    Manufactured light source; synonymous with bulb. Also,

  • Lamp Disposal

    When disposing of spent lamps, always consult federal, state, local and/or provincial hazardous waste disposal rules and regulations to ensure proper disposal. Plus,

  • Lamp Flicker

    Lamp flicker from magnetic ballasts can cause eye fatigue for some people.  And,

  • LED

    Light Emitting Diode.  Also

  • Light

    Radiant energy that is capable of producing a visual sensation.  And,

  • Linear fluorescent lamps

    In a fluorescent lamp, an electric arc passing between cathodes in a tube excites mercury vapor and other gases and produces UV radiant energy. Also, phosphor coating on the tube then converts this energy to visible light. Plus,

  • Low Pressure Sodium

    There are also HID bulbs with a sodium gas and produce a yellowish light.  And,

  • Lumens-Per-Watt (LPW performance)

    The number of lumens produced by a light source for each watt of electrical power supplied to the light source.  And,

  • Lumen Depreciation

    The decrease in lumen output of a light source over time.   Also,

  • Lumens

    A unit of the overall light output such as the quantity of light expressed in lumens.  And,

  • Luminaire

    A complete light fixture including lamp, reflector, ballast, socket, wiring, diffuser and housing.  In addition,

  • Luminance (L)

    Light reflected in a particular direction.  And,

  • Lux (lx)

    A unit of luminance equal to 1 lumen per square meter.  Plus,

  • Maximum Overall Length (MOL)

    The total length of a lamp, from top of bulb to bottom of base, typically expressed in inches.  Also,

  • Natural White

    Natural White is the closest to natural light created in the late morning to early afternoon and is the whitest of the lamp colors.  Also,

  • Nominal watts

    Represents the energy used to produce light. Watts= Volts x Amperes.  Plus,

  • Single-ended

    Lamps having a single lamp base or point of electrical connection.  And,

  • Spotlight

    A luminaire lamp that produces a narrow beam angle designed to illuminate a specifically defined area.  In addition,

  • Voltage (E)

    A measure of electrical potential, expressed in volts (V).  Also,

  • Warm Up Time

    The amount of time from ignition of the lamp to 90% light output.  And,

  • Warm White

    The color of the light from this lamp makes an area seem warmer and friendlier.   And,

  • Watt

    A unit of electrical power. Lamps are rated in watts to indicate power consumption.  Finally,