Colour Rendition Colour rendition is the ability of the eye to distinguish the true colour of an object - requires good colour balance from the light source. True colour is often considered as the way we see objects in natural daylight. Each type of lamp affects the rendition of colours:

• Incandescent lamps have all the colours - mainly enhance red, flatten blues and greens - provide good all-round colour rendition
• Mercury lamps enhance blues and flatten reds and greens
• Standard Warm White fluorescent lamps enhance orange and yellow - flatten reds, blues and greens. There is a wide variety of colour rendition from the fluorescent lamp range
• Multi-Vapor lamps enhance blues, greens and yellows flatten reds\
• Lucalox high pressure sodium lamps enhance yellows flatten reds and blues

REPLACE PRESENT LIGHTING SYSTEM LUMINAIRES AND LAMPS WITH A MORE EFFICIENT LIGHTING SYSTEM

The second approach requires replacing the present lighting system with a more efficient system - offers even greater savings, adding two levels of cost reduction:

• Cost level two - replace lamps and ballasts only
• Cost level three - replace lamps, ballasts, and luminaires - most expensive but offers greatest savings

Level two does not happen often, because by the time the lighting is considered for change the luminaires have completed their useful life and so replacing ballasts is not justified (like new wine in old bottles). Fluorescent Electronic Ballasts The main example of changing the ballast only is with high frequency electronic ballasts for tubular and compact fluorescent lamps. The normal European AC supply has a frequency of 50 Hertz. The lamp runs at this frequency. However, if a fluorescent lamp can be operated at a much higher frequency, 30 kilohertz or more, then the efficacy of the lamp is improved by up to 10%

An electronic ballast will change the supply frequency from 50Hz to 30+ kHz and if the lamp was run at its rated power would give more light. The more convenient approach is to under-run the lamp by about 10% so there is a saving in power consumed for the same light output as a conventional ballast. In this way the number of luminaires in the installation do not have to be changed. Where electronic ballasts are used the lamp performance must be checked with the gear manufacturer, because the lamp operating conditions are likely to be outside the normal standards laid down for that type. The performance data in GE literature may not be correct. Under-running the lamp normally is advantageous as lamp life and lumen maintenance will be improved. In the compact fluorescent range GE provides lamps complete with adaptors (which contain a ballast) so a direct comparison can be made

• 10W 2D with conventional adaptor: 14 total watts 650 lumens 10,000 hours life
• 11W Electronic Biax adaptor: 11 total watts 600 lumens