Principles and Terms

The old halogen lamps actually gave a good CRI, but of course, they were very inefficient, more expensive and give less lumens per watt compared to a chip that has lower CRI. Because of this, more power required to give a high color rendering from a fixture or lamp. 

This can be confusing if comparing lumen output of lamps or fixtures. So knowing the CRI of the light source is important to be able to make a fair comparison. 

CRI index should not be less than 70 in most applications in order to enable people to differentiate various colors and work more efficiently and correctly 

CCT- Color temperature defines the color appearance of a white LED. CCT is defined in degrees Kelvin; a warm light around 2700K, moving to neutral white at around 4000K, and to cool white, at 5000K or more. The warmer the colour, the less lumens per watt achieved and visa versa.  

One practice employed by some of the more disreputable manufacturers is to overdrive the chip to achieve more lumens per watt. They do this by pushing a higher current through the chips, via the LED driver. This will make the lamp/Tube/Panel appear bright compared to others, but the higher current will degrade the chip much faster and therefore the light output will diminish a lot sooner than correctly driven chips. 

LED drivers are without doubt, the ‘Achilles Heel’ of LED lighting and if a lamp fails prematurely, you can be 99.9% sure that it is the driver, not the LED’s. The drivers have electrolyte capacitors inside which can dry out if exposed to a continuous level of high operating temperature. The better quality drivers use larger and higher quality capacitors such as Rubycon from Japan. Also, if the lighting fixture is going to be used more than 12 hours a day, you should consider an external driver. Minding that HEAT is the main reason that LED lamps and drivers fail or lose brightness too soon.  

There is a lot of confusing information about the performance or light output of a chip. This usually expressed as lumens per watt, when the sellers advertise their goods. Claims of 100-125 lumens per watt for certain chips relate to the naked chip, before it is encapsulated and embedded into a fixture. This output will be reduced appreciably by the quality of the encapsulation, lenses and other components.  

The distribution of light on a horizontal surface. The purpose of all lighting is to produce illumination.  

The ratio of light produced to energy consumed. It's measured as the number of lumens produced divided by watt.