C

Cable Lighting Systems

Cable lighting systems are similar to track lighting, in that you get a selection of movable directional heads to choose from, but they are suspended from a cable strung across the room.

Canadian Standards Association

CSA, An organization that writes standards and tests lighting equipment for performance as well as electrical and fire safety. Canadian provincial laws requires that all electrical products sold for use in Canada must have a NRTL approval.

Can Lights

An informal (USA) name for recessed lights, a fixture mounted in a ceiling opening so that the housing of the fixture is hidden from view. The fixture’s trim assembly may be slightly protruding. Also known as pot lights in Canada, because of their general shape.

Candela

cd, The SI unit of luminous intensity, formerly called candlepower, it's the measurement of luminous intensity of a source in a given direction. The term has been retained from the early days of lighting when a standard candle of a fixed size and composition was defined as producing one candela in every direction. A plot of intensity versus direction is called a candela distribution curve and is often provided for reflectorized lamps and for luminaires with a lamp operating in them.

Candela Distribution Curve

A curve, representing the variation of luminous intensity of a lamp or luminaire, each lamp or lamp / luminaire combination has a unique set of Candela distributions that indicate how light will be spread.

Candlepower

An older terminology for luminous intensity, defined as the intensity in candelas of light from source, current practice is to refer to this simply as candelas.

Candlepower (Mean Spherical)

Mean spherical candlepower is the generally accepted method of rating the total light output of miniature lamps. To convert this rating to lumens, multiply it by 12.57 (4 pi).

Capacitor

An electrical circuit component which stores energy in electrostatic field, capacitors are used as power factor correcting or current regulating device and provide the control necessary to ensure proper lamp and ballast operation.

Carbon Monoxide Detectors

A carbon monoxide detector or CO detector is a device that detects the presence of the carbon monoxide gas in order to prevent carbon monoxide poisoning.

Case Quantity

Number of product units packed in a master case. Sometimes listed as total quantity of product in case, and sometimes listed as quantity of unit of sale packs, for example - 12 - 2pk = 24 lamps. Also known as Standard Package Quantity.

Cathode Resistance

Resistance of the cathode in a Fluorescent lamp. It is measured "cold" before the lamp is turned on "Rc" or "hot" after the lamp is turned on "Rh". The ratio of the hot resistance to the cold resistance is also measured "Rh/Rc".

Cavity Ratio

CR, Geometric proportions of the ceiling, floor and room cavities.

Ceiling Fan

A ceiling fan creates a breeze making hot weather more bearable, this wind chill factor makes the room feel several degrees cooler.

Ceiling Medallions

Ceiling medallions are decorative mouldings that elegance to a room, or as a way to hide an imperfection in your ceiling.

Center Beam Candlepower

CBCP, The intensity of light produced at the center of a reflector lamp, expressed in candelas.

Ceramic Metal Halide

CMH, A type of metal halide lamp that uses a ceramic material for the arc tube instead of glass quartz, resulting in better color rendering.

ChromaFit

A GE brand name for metal halide lamps designed to operate on HPS ballasts, allowing a user to switch from the yellowish color of HPS to the white color of metal halide without changing ballasts.

Chromaticity

Measure to identify the color of a light source, typically expressed as (x,y) coordinates on a chromaticity chart, See also Color Temperature.

Crystal Chandeliers

Crystal chandeliers are usually purchased for their beauty, elegance and sophistication, not the quanity of ambient light they create.

CIE

The International Commission on Illumination.

Circuit

The actual or intended path of current between a hot wire at the breaker and a neutral wire connected to the grounded neutral bar in the panel. Each loop that current makes through a single light, for instance is a circuit, but the most common meaning is of the "branch circuit", defined as everything fed by a given breaker or fuse.

Coefficient of Beam Utilization

CBU, The percentage of light from a floodlight which reaches the illuminated task relative to total beam lumens

Coefficient of Utilization

CU, In general lighting calculations, the fraction of initial lamp lumens that reach the work plane. CU is a function of luminaire efficiency, room surface reflectances and room shape.

Color

It refers to the spectrum of light. We talk about the color of an object the human eyes sees. Actually that color depends up on the amount and nature of the light received by that object and then reflected by it. If all the light were absorbed by an object, it would be black. If all the light ere reflected by the object, it would be white. There are no known surfaces that absorb all, or reflect all, of the light received. A partial reflection would yield different colors depending on the wave-length of the spectrum which is reflected. Thus, color is a characteristic of light by which a person may distinguish between two patches of color of the same size and shape.

Color Rendering

It is a general expression for the affect of a light source on the color appearance of object in conscious or subconscious comparison with their color appearance under a reference light source.

Color Rendering Index

CRI, A measurement of the amount of color shift that objects undergo when lighted by a light source as compared with the color of the same object when illuminated by a reference source of comparable color temperature. It, along with chromaticity coordinates, expresses the degree to which colors will appear natural under the light source selected. CRI ratings of various lamps may be compared, but a numerical comparison is only valid if the lamps are close in color temperature.

Color Temperature

Correlated Color Temperature - CCT, A number indicating the degree of "yellowness" or "blueness" of a white light source. Measured in degrees kelvin, CCT represents the temperature a theoretical incandescent object, like a filament, must reach to mimic the color of the lamp. Yellowish-white ("warm") sources, like incandescent lamps, and soft white fluorescent tubes have lower color temperatures in the 2700K-3000K range; white and bluish-white ("cool") sources, like cool white fluorescent tubes, and bright white CFL's have color temperatures in the 4100K-6000K range. The higher the color temperature the whiter, or bluer, the light will be. See also Chromaticity.

Compact Fluorescent Lamp

CFL, The general term applied to fluorescent lamps that are single-ended and that have smaller diameter tubes that are bent to form a compact shape. Some CFLs have integral ballasts and medium or candelabra screw bases for easy replacement of incandescent lamps. They have rated average life 5-10 times that of an incandescent lamp, and use about 1/4 of the power.

Contrast

The ratio of luminance of an object or detail to that of its immediate background

Cool White

A term used to denote a color of fluorescent lamps that have a color temperature of around 4100 K, and have a CRI of around 62.

Cornice Lighting

It is a term that applies to light sources that are shielded by a panel that is mounted parallel to a wall and attached to the ceiling. It distributes light all over the wall below. See also Cove Lighting.

Cost of Light

Usually refers to the cost of operating and maintaining a lighting system on an ongoing basis. The 88-8-4 rule states that typically 88% is the cost of electricity, 8% is labor and only 4% is the cost of lamps.

Cove Lighting

It is an expression for the effect of a light source that are mounted above a ledge or some form of recess that hides the light source from view and distributes the light over the ceiling and upper wall. See also Cornice Lighting.

Current

The flow of electricity, measured in amperes (A)

Current Crest Factor

The ratio of the peak lamp current to average lamp operating current (RMS). The lower the current crest factor is, the gentler the ballast is on the lamp.

Current Rise Time

A dimmer performance characteristic which indicated the degree of filtering provided within the dimmer.

Current Type

AC/DC, Whether the operational voltage is based on alternating current or direct current

Cut Sheet

Also called submittal sheet, specification sheet and spec sheet, A data sheet that shows fixture dimensions, descriptions, options, and photometric.

Cut-off Angle of a Luminaire

The critical viewing angle beyond which a source can no longer be seen because of an obstruction, angle from the vertical at which a reflector, louver or other shielding device cuts off direct visibility of a lamp. This generally results in better glare control.

Constant-Wattage Ballast

A type of HID ballast in which the primary and secondary coil are magnetically, not electrically, connected. Considered a higher-performance, higher cost ballast featuring excellent regulation