Specifications

“Lighting Systems Made Easy” Page 22
Glossary of Lighting Terms
A.C.
Alternating Current in which the flow of electricity reverses polarity (+/-, +/-) a number of times
a second. Normal U.S. power runs at 60 Hz., or reverses polarity 120 times a second, thereby
making 60 complete cycles in this time.
AMP
The measurement used to describe the amount of electrical current flowing in a wire or circuit.
Also the consumption of current by a lighting circuit. For lighting people, this term is most often
found when circuit breakers are specified or when working out the power consumption of a
lighting rig. Volts x Amps = Watts; therefore Amps = Watts/Volts.
ARC
An electric spark between two points. Used in very high output lights, such as xenon and
mercury vapor lamps, and strobe tubes. (The bright light that you see from most flash cam-
eras is a xenon arc.)
A different type of arc also occurs in a badly made electrical joint – electrical joint arcing can
heat up a power connection, destroy sensitive equipment and cause an electrical joint to fail.
AUTO CHASE
Lamps switched on/off in a sequence. The chase speed is set by a “pot” (or adjustable con-
trol), which provides manual up/down speed adjustment.
A.W.G.
Refers to the thickness of a wire, and determines its current carrying capability. The higher the
AWG number the thinner the wire and the less current it will carry without heating up or burning
out.
BARN DOORS
A number (normally two or four) or hinged flaps that are designed to selectively block off light
from the front of a lighting instrument. Barn Doors are used to shape a beam of light, cutting
the light off from selected areas.
BLACKOUT
A switch that, when pressed, will blackout the entire lightshow. Very useful when the operator
wants to show projectors or strobes on their own, or feature UV lighting or pyrotechnics. Usu-
ally controlled by means of one button, or switch, on a lighting console.
BREAKER
Normal usage term for a Circuit Breaker. A device that trips out, cutting off the AC power when
either too much current is drawn or when a complete short circuit occurs. For inductive
loads, the breaker has to be of a higher rating than for resistive load because of the back-EMF
generated by this type of electrical load.