Lighting Terms
by Curt Dunaway
of the Southern Colorado Aquarium Society, and plantgeek.net
Aquarticles
It can seem daunting at first. You get all these different terms thrown at you, and may
not know what they mean. Chris Terry of Peak Lighting Products, inc. (Colorado Springs,
CO.) was kind enough to address some of these questions.
1) Can you explain CRI
CRI - (Color Rendering Index) - Color rendering is the ability of a light source to
produce COLOR in objects. The CRI of a light is rated on a scale from 0-100. 100 is best
in producing vibrant color in objects. So in essence, a light with a CRI of 80 will
produce more vibrant color in the same object than a source with a CRI of 60, etc
2) Can you explain K rating
K - (Kelvin Temperature) - expresses the overall color of a light source itself. When you
describe a light as being either 'cool' or 'warm' it's actually the color temperature
(described as a temperature Kelvin, or K) that you're discussing. Lamps range in color
from about 2100K to 10000K. Lower color temperatures (ex 3000K) represent 'warmer' light,
higher (ex 4100K +) represent 'cooler' light.
3) Can you explain lumens
Lumens - Unit of measure for light energy. In other words, the total light output from an
electric source is expressed in lumens. The higher the Lumen Rating, the 'brighter"
the light to the human eye.
4) Can you give a brief explanation of watts
Watts - Used to measure power consumption. Often individuals confuse a "wattage"
rating with a "lumen" rating. Lumens describe the 'brightness' of a lamp,
"wattage" describes the power it takes (on your utility bill) to drive that
lamp. In general, however, a higher wattage lamp will normally produce more light (more
lumens) than a lower wattage lamp OF THE SAME TYPE.
5) What is the difference between a starter and a ballast?
Starter vs. Ballast - A starter (or ignitor) is used to initially strike an arc across a
lamp (fluorescent, HID, etc.) Not ALL types of circuits/lamps require the use of starters.
But in essence, once the lamp is started, the starter ceases to do anything. A ballast is
the regulating portion of the circuit. It regulates the operating voltage and current to
the lamp during all the time it's operating. Some types of lamps/circuits have the
starting mechanism built into the ballast itself, on other (often less expensive)
ballasts, the starter is a separate component.
6) What is the difference between an electromagnetic and an electronic ballast?
Briefly, an electromagnetic ballast starts and regulates the operation of a lamp via
copper windings encased in potting material. Conversely, electronic ballasts operate the
lamp via solid state components (transistors, capacitors, diodes, resistors, etc.)
Electronic ballasts are more energy efficient, smaller, lighter weight, operate cooler and
typically have a longer warranty. They are the state of the art technology, but cost a
little more to buy initially.
7) Can you compare T-12, T-8 and power compact bulbs as far a efficiency and
light output.
T12 vs. T8 vs. compact fluorescents - In general, fluorescents are about 4x more energy
efficient than incandescent (household type bulbs). The T12 lamps have been around forever
and have always been the standards. They operate on either electromagnetic or electronic
ballasts. T8's are a new technology - smaller diameter, operate ONLY from electronic
ballasts. When you're considering the energy efficiency of a light source, you're
describing it's LPW rating (Lumens per Watt). In other words, how many lumens of light
output do I get for every WATT it's costing me on my utility bill. T8's are slightly more
energy efficient (LPW-wise) than T12's. However, the BIGGEST energy savings is determined
by the type of ballast used (electronic vs. electromagnetic, for instance). Even within
the category of "electronic" ballasts, a wide range of energy efficiencies can
be chosen, the more expensive ballasts being more energy efficient. It's a 'pay up front'
vs. 'pay over the life of the ballast' scenario. Compact fluorescents come in 2 types,
those with electromagnetic ballasts vs. those with electronic ballasts. The same rules
apply to these lamps as they do to linear fluorescents
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