Leprecon LP-900 - Manual (Page 4)

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Leprecon/CAE, Inc. P.O. Box 430 Hamburg, Michigan 48139 810-231-9373
Leprecon®
Pro Lighting Equipment
OPERATING PRECAUTIONS
PROPER SYSTEM GROUNDING
An essential ingredient to safe, consistent, reliable, and quiet operation of a
lighting system is that the neutral and ground are not connected together at any
point in the lighting system or in the house service except at the main transformer
or service entrance, where the neutral is bonded to earth ground. Except at this
one point, neutral and ground are totally separate, totally isolated, and very
different terminals. The hot legs conduct power from the service through the
dimmers to the load. The neutral conducts current not balanced between the
legs from the load back to the main power source. It is a current carrying
conductor: By definition a potential difference exists between any two points of a
current carrying conductor. Current flows only when a potential difference exists.
The only point at which the neutral and ground are at the same potential when
any current is flowing in the neutral is at the one common point where the neutral
and ground are physically tied together.
The ground serves two purposes: Its primary purpose is to connect all conductive
parts of the system which can be touched by a person to earth ground potential
so that a person with some other part of his body grounded will not become a
conductor of electrical current (get hurt or killed) because of electrical leakage
(perfect insulation doesn’t exist) or because of a fault in equipment wiring.
Its secondary purpose is to shield the current carrying and electrical noise
generating components in a system by connecting chassis and enclosures solidly
to ground potential. In a situation where lots of sensitive audio equipment (much
of it improperly grounded) co-exists, this function is very important.
Connecting the ground to neutral at any point other than the single bonding point
at the main service causes neutral current to flow through the “ground”
conductor; it is no longer at ground potential; it is no longer a ground; its function
for safety and optimum system operation is impaired.
CONTROL GROUNDING
The control common should be totally isolated throughout the system, that is, not
connected to ground or neutral in the board, stage boxes, or dimmers. Some
dimmers have grounded control commons. This won’t be a problem in itself, but
will aggravate other possible faults.