Led Knowledge

Basic Lighting Knowledge

Lumen (lm)

Lumen is the international(SI) unit of luminous flux, a measure of overall light emitted by a light source.

Color Temperature / Correlated Color Temperature (CCT)

A black-Body radiator will have different color when it is heated up to different temperature(in kelvin). The temperature at which the heated black-body radiator matches the color of the light source is the color temperature of the light source.

Efficacy (lm/W)

Efficacy is the effciency of a light source to convert electricity power to light expressed in lumen output per unit power input (watt)

[Efficacy = lumen / wattage]

Design Life Time

Design life time is the average life of lighting product when it is operated at nominal lamp voltage, current and controlled working environment. Actual lamp life time varies because of difference from those rating condition.


Dimming LED lamps can save energy and changes the visual appearance and mood of your space. You can use a dimmable LED lamp in a non-dimmable circuit. You should NOT use a non-dimmable lamp in a dimmable circuit as it may cause damage to the lamp and or circuit.


Color Rendering Index (CRI) is the measurement of how colors look under a light source when compared with sunlight. The index is measured from 0-100, with a perfect 100 indicating that colors under the light source appear the same as they would under natural sunlight.

This rating is also a measurement in the lighting industry to help discern naturalness, hue discrimination, vividness, preference, color naming accuracy, and color harmony.

Warm White or Cool White?

Correlated Colour temperature (CCT) in lighting describes how the colour of the light appears from a lamp, measured in kelvins (K).

Imagine a scale from 1000K (very red)  to 10,000K (very blue)  (actual scale is wider).  The higher up the scale you go, the closer the light resembles blue daylight.

The Range of Color Temperature

The three primary types of color temperature for light bulbs are: Soft White (2700K – 3000K), Bright White/Cool White (3500K – 4100K), and Daylight (5000K – 6500K).

The higher the Degrees Kelvin, the whiter the color temperature. Although the whiter lights will appear “brighter” than those of a lower Kelvin reading, the amount of Lumens (measurement for brightness) does not change, and true brightness is not affected.

Confusingly, color temperature does not describe the actual temperature of the lamp itself but the color it produces and counter-intuitively; the higher the color temperature the “cooler” a lamp will look. 

Put simply, color temperature is based on how the color of heated metal changes as its temperature is increased - turning from red to yellow then blue.  You can then determine the temperature of a heated metal by its color.  This range of colors at different temperatures has become useful for describing the color tint of white light.  The color of light from an LED lamp is approximated or “correlated” to this scale.      

LED Technology

The advantages

LED lighting products perform better in most circumstances, here are some of the advantages:

  • Save up to 85% on energy costs, a major difference, when compared to filament or halogen lamps such as GU10s
  • Save 12-50% when compared to CFL
  • A reduction in energy use lowers your carbon footprint
  • LED lamps light up instantly - unlike many CFL bulbs
  • Produce much less heat than filament bulbs
  • Are mercury-free (unlike CFL bulbs)
  • LED lamps last much longer (20X longer that a filament bulb) leading to a reduction in maintenance costs
  • For the home, retro-fit LED lamps will work in your existing light fittings and can be installed in minutes, so you can enjoy the benefits immediately

Health - Benefit to your Skin, Eye, Breath

  • LEDs do not generate UV rays. It is very safe when we use LEDs in desk lamp or table lamp where lights can be very close to human skin.
  • LEDs generate direct light. LEDs light up instantly without flickering, and you don’t have to wait for them to warm up to get the full brightness.
  • 100 % safe materials, free from heavy materials. LED lights will not “burn out”, free from explosion.

LEDs are cool to touch, because they don’t generate much infrared (IR) energy, don’t generate heat within the semiconductor structure.

Environmentally friendly
LEDs do not contain hazardous mercury or any other toxins. They do not emit Ultra-Violet (UV) ray and generate less heat than CFLs, which also means air conditioning systems have less heat to dispose of. They can last up to 30 times longer than average incandescent light bulbs, result in less landfill waste. When you enjoy the savings on energy, you are also saving our Earth by reducing waste and CO2 emissions.

Financial saving and Long Lasting
Relatively long useful life. They last at least 25,000 to 50,000 hours and still remain 70% of its initial lumen output; compare to incandescent light bulbs at 1000-2000 hours and compact fluorescent light at 8000-10000 hours, depending on the conditions of use.

LEDs are the most efficient lights on the market today; they emit more lights per watt than any light bulbs out there. Typical performance of incandescent is around 11~15 lumens per watt compare to LEDs with a min. output of 60 lumen/ watt or above. This is a saving of at least 80% of energy. They are much more efficient than incandescent or fluorescent bulbs.

LEDs do not contain fragile filament or glass body; this makes them vibration resistant and durable.





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