Low Voltage Lighting

A high voltage incandescent lamp requires a relatively high resistance filament for a particular Wattage rating. This means the filament is long and the globe is large. The 12 Volt dichroic lamp filament can be of much lower resistance for a particular Wattage, as the applied voltage is much less. This means the filament and globe can be smaller allowing the use of a halogen gas which increases the filament life. Because the inside of the globe is very close to the filament, the temperatures are very high. Ordinary glass would not stand the heat so quartz must be used. The higher filament temperature gives a higher colour temperature and a whiter light than non halogen incandescent types and greater lumens per Watt.

The small size of the lamp makes it possible to integrate a small reflector to allow precise control of the beam. Lumen maintenance over the lamp life is nearly 100%.

The reflector used is a dichroic type which allows much of the infra red energy (heat) generated by the filament to pass through the back of the reflector and into the ceiling. This reduces discomfort from heat beamed down from the lamp. The colours visible in the back of the reflector have nothing to do with the colour rendering of the lamp, but are caused by the dichroic coating.

Note:
An installation of two 50 Watt dichroic lamps and transformers will actually consume more power than one GLS 100 Watt lamp because the transformers are wasting about 12 Watts each (24% more power). But we will get more light for our input power from the low voltage system.

	GLS gives 1000 lumens for 100 Watts (10 lumens per Watt)
	Low voltage lamp gives 950 lumens for 62 watts (15 Lumens per Watt for the system)
	50 Watts to lamp involves 12 Watts in the transformer (50 +12=62 Watts total)

Advantages

	Excellent colour rendering (CRI= 100)
	Instant start
	Lamp life 2000 to 5000 hours
	Higher lumens per Watt than non halogen filament lamps
	Excellent lumen maintenance
	Can be dimmed

Disadvantages

	Power loss in transformer creates heat (less waste energy with electronic transformer).
	Ultra violet content of light can damage some surfaces (use glass covered lamps).
	Voltage fluctuations can reduce lamp life. An increase in mains voltage of 5% above 240 will reduce lamp life by 50%.
	Lamp costs are greater than standard incandescent
	Touching of the quartz lamp may lead to premature lamp failure