Talk the talk and walk the walk. Brush up on your lighting terminology. Time to find out what those words really mean.

BALLAST	FOOTCANDLES VS. CANDLEPOWER
COLOR	LAMP VS. BULB
EFFICICACY VS. EFFICIENCY	LAMP LIFE
ENERGY	POWER QUALITY
	WATTS VS. LUMENS

BALLAST

The ballast is an electronic device that converts electrical current coming from outside the Light Capsule to the right quantity of voltage and amperage required to start the lamp safely and efficiently. The ballast then stabilizes the current, regulating the pace of electric flow after startup to ensure continued, safe operation. In fact, that's how the ballast got its name. Long before lighting technology was developed, in the days of ships and sails, the ballast was used to stabilize ships in choppy seas.

Compact fluorescent technology requires ballasts that are either magnetic or electronic:

• Magnetic (core and coil) ballasts are the least expensive option but are considerably heavier than electronic ballasts, require a few seconds to light and often produce a low hum.
• Electronic ballasts are lightweight, allow the lamp to start instantly, and consume significantly less energy.

COLOR

The color of light is determined by its wavelength. The range of wavelengths that comprise visible light make up only a small portion of the entire electromagnetic spectrum. The entire electromagnetic spectrum represents all of the different wave lengths, including radio waves, micro waves to infrared, visible light, ultra-violet light, x-rays and finally gamma rays. White light contains all the colors of the visible spectrum. Two ratings are commonly used to describe the color properties of lamps:

• Color temperature is the color appearance of the light produced by a lamp and the color appearance of the lamp itself. It is measured with the Kelvin scale (K). A lamp with a low color temperature will have a "warm" appearance (red, orange, or yellow). Conversely, a lamp with a high color tem- perature will have a "cool" appearance (blue or blue-white).
• Color Rendition is a measure of how the lamp influences the color appearance of the objects which are being illuminated. It represents the ability of a lamp to render colors accurately and to show color shade variations more clearly. High color rendition allows us to see objects as we would expect them to appear under natural sunlight. Color rendition is measured via a complex process on the Color Rendering Index scale (CRI), ranging in value from 0 to 100.

EFFICACY VS. EFFICIENCY

Efficacy is the lamp output per unit of energy input to the lamp. Therefore, it is the ratio of lamp output to wattage consumption, expressed in lumens per watt (LPW).

Efficiency is the absolute percentage of light produced within a fixture that is not absorbed within the fixture, but actually leaves the fixture.

ENERGY

Energy is the electric power input, measured in kilowatt-hours (kwh).

FOOTCANDLES VS. CANDLEPOWER

A footcandle is a measure of the quantity of light (illuminance) which falls on a surface - a measure of the lighting in a room.

Candlepower describes the light intensity of a lamp in a certain direction. It is a measure of the light source itself, measured in candelas.

LAMP VS. BULB

The lamp is the actual light-producing component inside the bulb.

The bulb is the decorative glass or plastic housing that diffuses the light distibution.

LAMP LIFE

Lamp life is the lamp's average lifespan measured in hours. Rated lamp life for a fluorescent lamp is based on hours-per-start. Hours-per-start is the amount of time the lamp is on before it is turned off and then on again. (Panasonic measures 2.5 hours on and 30 minutes off). The more frequent a lamp is turned on or off the lower the lamps rated life. The lamp loses some material needed for startup and operation every time it is turned on.

Fluorescent lamps on average last ten times longer than incandescent lamps.

Lamp lumen depreciation (LLD) is the reduction in light output from a lamp due to the aging of fluorescent lamp phosphors or incandescent lamp filament evaporation.

POWER QUALITY

• Total Harmonic distortion (THD) is a measure of the degree by which a sinusoidal wave shape is distorted by harmonics. Harmonics are the higher multiples of the fundamental frequency, and, they can potentially interfere with the operation of electrical devices, such as radios, televisions and other sensitive electronic equipment in hospitals.
• Power factor (PF) is a measure of how effectively the ballast converts the incoming electric current into useable power. It is represented by the ratio of real power (watts) to apparent power (volt-amps).

WATTS VS. LUMENS

A watt is a measure of the amount of electrical power required by a product to operate at any given instant - the power going in the lamp.

A lumen is a measure of the amount of light produced by a lamp - the light coming out of the lamp.