20 Researching the requirements

Commercial power conditi6ning

If the quality of the commercial power source continuously meets the SL-1
system requirements listed in this section, a power conditioner is not
required, however, where the commercial power is of poor quality and
cannot consistently meet the SL-1 system requirements, a powerconditioner
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may provide some improvement.
Note:
When using power conditioning equipment, simply install the
equipment in series with the commercial power feed. Do not modify
the SL-1 system grounding scheme.
Grounding
Essential to trouble-free system operation and the safety of personnel is the
employment of proper grounding. The SL-1 system has several different
grounds and signal returns that are generally referred to as grounds: logic
return (for DC systems), AC “green wire” ground (in AC systems), and the
personal hazard equipment ground.
The SL-1 system does not, by design, need an AC isolated ground (IG)
system (though this may be required by local codes), but it does need a
single point ground system. This means that each of the various grounds
from each of the columns should terminate at a single connection point
before attaching to the actual ground reference at the main AC panel or
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transformer. The single point ground may be implemented either by use of
the isolated ground bus in the AC panel, or by a separate logic return
equalizing bus for battery returns and logic returns where a non-isolated AC
system is used.
The SL-1 system power must originate from the supply service (main AC
panel or transformer) where the ground conductor and the neutral conductor
connect and are referenced to the main building ground (MGM). Cold
water pipes and ground rods should only be used to improve the ground
reference of the building’s main service panel. Do not use the MGM as the
ground reference for the SL- 1 system.
The DC resistance of the system ground conductor, which runs from the
SL-1 to the main building ground, should be as close to zero as possible ,:rzZ?
with the maximum total resistance on all runs within the building not to
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exceed 0.5 ohms.
installation planning 553-3001-120
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