Glossary

Ambient Temperature - Describes the temperature of the air around a light fitting. The performance of an LED light is affected more by ambient temperatures than other forms of light. Heat-sinking helps maintain the lifespan of LED lights.

ANSI - American National Standards Institute.

Amperes or Amps - Measure of electrical current flow in a circuit.  Amps are considered when sizing electrical wiring.

Beam Angle - As defined by IES LM-79, the beam angle is the angle at which light decreases to 50% of its maximum, with the maximum typically occurring at nadir (center-down).  Beam angle may be defined along two axis of the light source. 

CFL - Compact Fluorescent Lamp. A small fluorescent light, used as a more efficient alternative to incandescent lighting.

CCT - Correlated Color Temperature.  For predominantly white light sources, CCT is the temperature of a blackbody with equivalent color cast, as defined by ANSI 78.377. .   Color temperature describes whether a light source appears ‘warm’ or ‘cool’ – indicated by the CCT. Lamps with a warm appearance have a CCT of 2700-3500K, and are considered appropriate for domestic settings; cooler lamps might be 4000K, and are used more often in offices and retail. The higher the color temperature, the ‘cooler’ the appearance.  5000K are generally used in industrial high bay applications.  The Sun has a CCT of 5700.

Dali - The Digital Addressable Lighting Interface is a protocol for lighting controls and dimming agreed by major manufacturers. Originally developed by Philips, it is now an open technical standard, IEC 62386.

Diffuser - A diffuser is applied to a light source to spread light more evenly. It is made of translucent glass or plastic, and gives a much softer light. This is useful for general lighting, where the light needs to be less directed.

DLC - DesignLights Consortium, the governing body that certifies the quality and efficiency of LED Lights. It is a standard similar to Energy Star. Where as Energy Star is for home owner type products, DLC is for commercial grade LED products. A DLC Qualified product may be eligible for rebates. Your local utility designates whether you are eligible for rebates or not, and it varies between utility companies. Currently there are two standard, DLC Standard and DLC Premium. DLC Premium is more efficient and will save you more money in terms of operating costs. 

DOE - The United States Department of Energy.

Efficacy - Ratio of the amount of light produced by a lamp to the power required to produce it. Measured in lumens per watt (lm/W).

EIA - The United States Energy Information Administration.

Foot-candle - A non-standard measurement of illuminance or light intensity. A unit of illumination (now little used) equal to that given by a source of one candela at a distance of one foot (equivalent to one lumen per square foot or 10.764 lux).

Fluorescent - A type of light sources based on exciting a mercury plasma, typically in a glass tube. Fluorescent lights contain mercury gases which are released if the lamp is broken. Mercury gas can be dangerous, so LEDs provide a safer and more environmentally friendly option.

GaN - Gallium Nitride, the semiconductor most prevalent in the fabrication of the LED chips used in white LEDs.

Halogen lamp - Also known as a tungsten halogen, quartz-halogen or quartz iodine lamp, is an incandescent lamp consisting of a tungsten filament sealed into a compact transparent envelope that is filled with a mixture of an inert gas and a small amount of a halogen such as iodine or bromine.

Heat Sink - A heat sink is used to take heat away from certain parts of an electronic circuit. Because LEDs are sensitive to heat, a heat sink is often an important part of an LED luminaire. Heat sinks help to preserve the lifespan of LED lights.

HID - HID stands for High Intensity Discharge. It describes a kind of light source used in warehouses (high bays), football stadiums, and large public areas. They are typically very bright and are also energy efficient. They are often used as car headlights.

HPS - High Pressure Sodium. A traditional lighting method for outdoor lighting, recognizable by a heavy orange glow.

SSL - Solid State Lighting is a term which refers to lights based on semiconductor opto-electronic devices. LEDs are a type of Solid State Lighting.

THD - Total Harmonic Distortion is a measurement of a electrical signal pollution that a load presents to a power system. THD is one characteristic used to describe the power quality of electric power systems such as ballast or driver.  High THD can cause disruptions in power service. THD is typically requires a special measurement device, though in some cases, lamps with poor THD will create noise that can be heard.

Troffer - A troffer is a rectangular light fixture that fits into a modular dropped ceiling grid (i.e. 2‘ by 2‘ or 2‘ by 4‘).  Troffer fixtures have typically been designed to accommodate standard fluorescent lamps (T12, T8, or T5), and can now be easily retrofitted with TLEDs to reduce even more power consumption.

UL - Underwriters Laboratories. A global independent safety science company that provides safety-related certification, validation, testing, inspection, auditing, advising and training services to a wide range of manufacturers, retailers, policymakers, regulators, service companies, and consumers.

UV light - Ultra violet light is found in sunlight and artificial light such as fluorescents.

Volts - Unit of electro motive force.

Watts - The standard delivered units of electrical power or energy per unit of time, measured in Joules per second. It is the starting point for how you are charged for energy.