Lighting Terms

Lumen

A lighting measurement used to describe the amount of light a luminaire produces. The higher the number, the more light is produced and therefore brighter the luminaire. Lumens are a good way to compare lighting sources and offers a benchmark for evaluating lighting performance. We try and provide lumen data for all our LED fittings where possible. Special equipment is required to take lumen measurements where the luminaire is placed in an enclosed area to capture all the light that is produced. The same test also provides an .IES File

Lux

A lux is a unit of standard measurement used to determine how much light is present at a particular point or surface. Lux is used to determine the brightness of a surface. Factors such as reflectance, distance, beam angles and qty of luminaries will all impact how much light is measured at a particular point. This measurement can be taken with a Lux meter.

Efficacy

Efficacy is a term used to describe the relationship between energy usage and light output. It is a ratio used to express how well a luminaire produces light. The ratio is expressed as lumens / watt. It is useful for comparing lighting efficiency. However when comparing efficacy figures between LED suppliers it is important to compare the right figure. There are two main figures commonly quoted which are listed below, sometimes it can be unclear which figure has been quoted.

LED Efficacy

This refers to the LED chip Efficacy. This figure refers specifically to the LED chip and does not take into consideration any other components. This figure is always higher than Luminaire Efficacy. This measurement is used to compare LED chips only.

Luminaire Efficacy

This figure measures the total efficiency of a luminaire. It includes all components including control gear and power supplies. It is more accurate, however the figure is generally lower due to the inefficiencies created in transforming electrical current. Component selection can significantly alter Luminaire Efficacy. This figure is used to measure LED luminaires.

Example

A LED Efficacy figure is provided from an LED manufacturer at 110lm/w. If we integrated this chip into a LED luminaire we could reduce the current via control gear. This would reduce the light output, however it would increase the lifespan. Therefore the total efficacy of the LED fitting would be reduced. 80lm/watt would be the total fixture, however the fitting is using a 110lm/w LED as the light source.

What we quote...

We always quote the Luminaire Efficacy to portray the real figure of luminaire efficacy. A LED is never used without other components and therefore it is irrelevant when comparing market ready LED products. If you are using this figure to compare LED fixtures it is important to know which figure has been used for accurate comparison.

L.E.D (Light Emitting Diode)

LED is an acronym for Light Emitting Diode. A LED is a semiconductor that converts electrical current into light. These light sources are long lasting, durable and energy efficient. They do not contain filaments or other fragile components such as glass and are referred to as Solid State Lighting. LEDs are available in many different types and configurations.

SSL (Solid State Lighting

A light source that creates light through diodes instead of filaments, plasma or gas. SSL creates visible light more efficiently with reduced heat generation. They also are more durable being resistant to vibrations or breakage. LED, OLED and PLED are all examples of Solid State Lighting.

Voltage

Voltage is a measurement of the energy contained within an electric field, or circuit at any given point. Voltage is the difference between two electrical charges between two points in a circuit. In Australia the most common voltages are:

  • 12v DC - Caravans | Motorhomes | Marine | Camping | Solar
  • 24v DC - Trucks | some Motorhomes | Marine | Solar
  • 48v DC - Trains | Mining applications | Other specialised applications
  • 220v AC - Mains household voltage

Amperage

Amperage refers to the strength of an electrical current. It is the measure of the amount of electricity (flow of electrons) passing a point in a given time. It can be calculated by the following formula. Watts / Voltage = Amps. This measurement is useful to calculate loads for transformers or calculating running time for a load on a battery.

Example

6watts / 12v = 0.5A

Constant Current

Constant current refers to a system that provides or requires constant current. The voltage can vary however the current is controlled by a current regulator. Some LEDs require constant current to operate, mostly constant current LEDs are high power. Increases LED lifespan and performance are generally achieved by constant current.

Beam Angle

A beam angle of light is the conical width of light emitted from a light source. It is measured in degrees. The higher the number, the greater the spread of light, The narrower the number the narrower the spread. The points are determined by where the light has dropped >50% of the maximum light emitted. The beam angle will affect how much light reaches a particular surface depending on the mounting distance.

Beam Angle

How Beam Angle is Defined

CCT (Colour Correlated Temperature)

CCT is a rating system designed to categorise visible light. It is measured in Kelvins and simply refers to how "bluish white" or "orangish light" (consider Candlelight vs Fluorescent). The higher the rating the "colder/bluer" the light appears. Anything above 5000k is considered "cool". The lower the rating the "warmer/yellower" the light appears. Anything below 4000k is considered "warm". (see image below)

Watt

A unit of measurement of electrical power. One watt is one ampere of current flowing at one volt. It is used to determine how much electricity a product uses when. The higher the number, the more electrical energy it is converting.

.IES Files

A computer file that contains IESNA photometric data. This file can be used to represent a light source in a computer program such as dailux. We try and provide IES files for our products where possible. If none are available please contact us for more information.