Lighting Terminology

Ballast:  A component required by fluorescent and HID lighting fixtures. It controls the voltage and electric current provided to the lamp during ignition and operation, preventing overheating or premature failure. Depending on their internal construction, ballasts can be either magnetic or electronic.

COLOUR TEMPERATURE (Kelvin):  A hot object radiates a specific range of wavelengths that appear as a particular colour depending on the object’s temperature. The temperature is expressed in Kelvin (K), the scientific temperature unit.  The Kelvin temperature equivalent is used to describe the lamp’s colour. Lamps generally vary from about 2500K, which is quite yellow through to 7000K, which is  bluish.Standard lamp temperatures are 3000K  Warm White,  4000K  Neutral White, 5000K Cool White. Colour temperature can change how other surface colours look.

BC22 LAMP: a lamp with a bayonet base which is 22mm in Diam

E27 LAMP:  a Lamp with a screw in base which is 27mm Diam.

Ceiling Cavity: The portion of a room that is above the lighting fixtures.

Color Rendering Index (CRI): A metric used to describe how faithfully a light source can render the true colors of objects and spaces, where natural light sources like the sun have a perfect index of 100. Using lamps with a  CRI of 80 is good for general illumination  CRI 90 is good for colour critical spaces such as galleries

DALI : Acronym for Digitally Addressable Lighting Interface, a communication protocol for lighting automation, which enables individual dimming of individual luminaries

Driver: Piece of electronic equipment that transforms the main supply voltage into a lower DC voltage that is appropriate for LED lighting. Some LED lamps have a built-in driver, while others require one to be connected externally, just like the ballasts used by fluorescent and HID lamps.

Electronic Ballast: A subtype of ballast that uses power electronics to provide a high-frequency voltage and controlled current for fluorescent lamps. Electronic ballasts are lighter and more efficient than magnetic ballasts, and they eliminate humming and flickering issues.

Electronic Transformer: Smaller and lighter than magnetic transformers, electronic versions use electronic switching and special dimmers to step the line voltage down to the lamp voltage.

Glare: Visual impairment caused by a bright source of light, directly visible or reflected by a surface. There are two types of glare:

1: Discomfort glare causes an instinctive reaction to close the eyes and look away. This is the type of glare felt when exposed to a potent HID light or when the sun is directly visible through a window.

2: Disability glare impairs vision, but does not cause the same reaction as discomfort glare. If a light source gets reflected on your laptop screen, for example, it does not bother your eyes but distinguishing objects on the screen may be impossible.

Halogen Lamp: An improved version of incandescent lamps, where the glowing filament is contained in halogen gas, hence its name. Halogen lamps are around 25% more efficient than their incandescent counterparts.

Illuminance: The luminous flux on a surface, per unit of area. The illuminance requirements of built environments are determined by their intended purpose, and there are two common units of measurement:

Incandescence: Light produced by heating a material; Examples include the glow of a candle, an incandescent filament lamp, a shooting star, etc.

Kelvin (K) Measurement unit for temperature, although in the lighting industry it is more commonly used to indicate the correlated color temperature (CCT) of light sources.

Lamp Lumen Depreciation (LLD): A progressive reduction in the luminous output of a lamp throughout it service life.

LED: Acronym for light-emitting diode, a solid-state component that emits light when exposed to electric current. LED lighting represents the state-of-the-art in the industry, outclassing most other types of lighting in terms of energy efficiency, design flexibility and colors of light available.

Light Engine: describes the actual source of illumination, whether it is LED or incandescent lighting

LUMINOUS INTENSITY (Candela)  Luminous intensity is a measurement the light radiating from the lamp in a particular direction, disregarding the intensity of light in other directions. The Candela figures for a source need to be given for specific directions but are independent of distance from the lamp.  Manufacturers provide charts showing the luminous intensity of a lamp in every direction from the source. These charts can be used to calculate the total luminous flux and the illumination intensity surrounding the lamp.

LUMINOUS FLUX (Lumens)  The perceived total amount of useful light from a source is the sum of the Candela measurements in all directions. It is measured in Lumens (lm). The figure is also independent of distance from the lamp and says nothing of the direction of the light, the intensity of the source or the brightness of an illuminated surface, just the total visible light in all directions.

Lumen: Measurement unit for the lighting output of lamps or fixtures. The total lumens emitted and their spatial distribution are of paramount importance when creating appealing and luxurious indoor spaces. In lighting, lumens can be compared to miles traveled and watts can be compared to fuel consumption.

Luminaire: A complete and functional lighting fixture. A luminaire includes the lamp, the ballast or driver, internal wiring, reflectors, lens and any additional components required to deliver light.

Mounting Height: Depending on the application, mounting height can have two possible definitions: 

1: Distance between the bottom of the fixture and the work plane.   2: Distance between the bottom of the fixture and the ground.

OLED: Acronym for organic light-emitting diodes, flexible polymers based on organic carbon molecules, where the light source is spread across a surface as opposed to a point source.

Pendant Light / Pendant Fixture / Pendant Lamp: A lighting fixture that is designed to hang from the ceiling, and which often uses a shade to prevent glare. Pendant lights can be used for both general and task lighting.

Task Lighting: Lighting fixtures with the goal to improve visibility in an area where specific tasks will be carried out, hence their name. The use of under cabinet lights for food preparation areas in kitchens is an example of task lighting.

Universal dimming: refers to the method in which a lamp can by dimmed using both leading and trailing edge control.  Universal dimmers tend to operate better with electronic transformers for AC LED lamps.

Voltage: The electric potential difference between two contacts. Voltage drives electric current through lighting fixtures and other appliances, just like pressure drives the flow of water in plumbing installations.

Watts to Lumens: To convert watts to lumens, multiply the power (P) in watts (W) with the luminous efficacy (η) in lumens per watt (lm/W).