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SELECTED LIGHTING DEFINITIONS
ANSI CODE: American National Standards Institute has established a 3-letter code for stage lighting lamps. Lamps ordered by their ANSI code from different manufacturers should have interchangeable fit and function.
COLOR TEMPERATURE: Measured in degrees Kelvin (ºK). Lamps rated at 3200ºK produce clear white light. Lower temperatures will tend to give yellowish light. Color temperatures above 3200ºK with prolonged exposure may cause ultraviolet irritation to skin and eyes.
COMPLIMENTARY COLORS: These are 2 lighting colors when mixed together in equal amounts on the same surface will yield white light.
CONTROLLER: Lighting controls for stage lighting systems. Typically, providing multiple control channels and scene mixing/settings with master level/cross fade functions. The lighting controller drives light dimmers similar to the way an audio mixer drives audio amplifiers.
DIMMER: A device that adjusts the light emitted by a light source. This device installs between the load (light fixture) and the service electrical power source. A controller may be required to provide adjustment commands signaling light level changes.
ELECTRICAL FORMULAS: Basic electrical calculations can be made for:
VOLTS (E), E = W÷I: Amperes (I), I = W÷E: Watts (W), W = E•I. As an example, 10 fixtures with 500 watt, 120 volt lamps will require a 41.6 ampere current service. CALCULATION: 10 fixtures @ 500 watts = 5000 watts. Using Amperes formula: I = W÷E, I = 500÷120, I = 41.6
FILAMENT SHOCK: The lamp filament receives a thermal shock when electrical current is initiated to a cold lamp which will significantly shorten the operating life of a lamp. Some dimmers provide an automatic lamp warm up cycle (softstart) to minimize the turn-on shock and extend the life of the lamp.
FOOTCANDLE (fc): A measure of lumens per square foot. As an example, a 6' x 8' screen receives 800 lumens from a projection lamp/lens. The average light density on the screen is 20 foodcandles. CALCULATION: a) 6' x 8' = 48 sq. feet screen size, b) 800 lumens ÷ 48 sq. feet = 20fc
GEL MATERIAL: Typically, a polyester film translucent sheet that is color dyed to be stable at high temperature when used with stage lights. Placed in front of a strong white light beam, colored light is projected on to the object of focus. 100's of colors are available for an endless array of effects.
INCANDESCENT LAMP: Produces illumination that is slightly yellow compared to quartz lamps. Used more for architectural lighting, the incandescent operates at a cooler temperature. These lamps have a lower initial cost but with a shorter life.
INVERSE SQUARE LAW: Mathematically, illumination from a light source varies inversely with the square of the distance from the measuring point. As an example, a light source produces 6000 lumens. At a distance of 10 feet, the light density would be 60 footcandles, and at 20 feet the light density would be 15 footcandles. CALCULATION: a) @ 10 feet = 6000 ÷ (10)(10) = 60 footcandles, b) @ 20 feet = 6000 ÷ (20)(20) = 15 footcandles
LAMP RING: With certain dimmers, PAR lamp filaments will vibrate at mid-dimming cycle creating an audible ring. This ring can be very noticeable in quiet environments. Other lamp styles are dampened and will not produce audible ringing.
LUMEN: A quantity measurement of light illumination from a light source. The original measurement was made using a "standard candle" placed at the center of a 1-foot radius hollow sphere. The light spread over a 1-square foot area of the sphere was 1 lumen. The surface area of the sphere is 12.57 sq. ft., so the candle is said to produce 12.57 lumens. One-foot lumen is equal to 1-footcandle (fc).
LUX: A metric quantity measurement of light illumination from a light source. 1 lux = .093 lumens. 1 footcandle = 10.76 lux
MICRO-PLEX: An interconnect digital control technology common to NSI (Nova Systems, Inc.) controllers and dimmers. A standard microphone cable is used to carry the controller digital commands to the dimmers (daisy chaining between dimmer packs) and sending phantom power voltage from the dimmer to power the controller.
PIXEL: A unit of measure formed by a rectangular grid of small squares, where each square is considered a pixel. Televisions, computer monitors, and projectors etc. use pixels as units of measure.
QUARTZ LAMP: Also referred to as Tungsten Halogen lamps, these produce whiter light, more lumens and last up to six times longer than incandescent lamps. Only fixtures rated for quartz are designed for the higher operating temperatures. Color gels work best with quartz lamps for truer color presentation.
WIRE SIZES: Electrical wire carries current (amperes) for the supply (electrical outlet or power panel) to the load (dimmer, lighting lamp etc.). When the wire is too small, resistance to the current flow is converted to heat, resulting in a loss in voltage delivered to the load. This may cause the circuit breaker to throw. For wire lengths under 100 feet at 120 volts, using copper wire, use the following as a guide: (smaller AWG number = larger wire size):
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CURRENT @ 120 VOLTS |
LOAD (WATTS) |
WIRE SIZE |
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20 Amps or less |
2400w |
12AWG |
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15 Amps or less |
1800w |
14AWG |
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6 Amps or less |
720w |
16AWG |
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