Electrical Installation 13
The display must be properly grounded according to local and national codes or the warranty
will be void. Proper grounding is necessary for reliable equipment operation and protects the
equipment from damaging destructive disturbances and lightning.
Daktronics recommends a resistance-to-ground of 10 ohms or less. The electrical contractor
performing the electrical installation can verify ground resistance. Daktronics Sales and
Service personnel can also provide this service.
The display system must be earth-ground. The material for an earth-ground electrode differs
from region to region and may vary according to conditions present at the site. Consult local
and national electrical codes.
Daktronics does not recommend using the support structure as an earth-ground electrode;
concrete, primer, corrosion, and other factors make the support structure a poor ground.
Note: The support structure may be used as an earth-ground electrode only if designed to
do so. A qualified inspector must approve the support structure and grounding methods.
There are two types of power installation: installation with ground and neutral conductors
provided, and installation with only a neutral conductor provided. These two power
installations differ slightly, as described in the following paragraphs:
Installation with Ground and Neutral Conductors Provided
For this type of installation, the power circuit must contain an isolated earth-ground
conductor. In this circumstance, do not connect neutral to ground at the disconnect or at the
display as this would violate electrical codes and void the warranty.
Use a disconnect so that all ungrounded lines can be disconnected. The National Electrical
Code requires the use of a lockable power disconnect within sight of or at the display.
Installation with Only a Neutral Conductor Provided
Installations where no grounding conductor is provided must comply with Article 250-32 of
the National Electrical Code. If the installation in question meets all of the requirements of
Article 250-32, the following guidelines must be observed:
Connect the grounding electrode cable at the local disconnect, never at the display
driver/power enclosure.
Use a disconnect that opens all of the ungrounded phase conductors.
Both power and signal cables are routed into the scoreboard from the rear via separate
conduits. All power and signal wiring terminates at the master driver enclosure. Note that
systems with radio control do not require external signal wiring.
Look for a warning label similar to Figure 13 to locate the
front access panel to the driver enclosure. Remove the screws
or loosen the latches to open the access door panel. Remove
the metal cover of the driver enclosure to expose the driver
components (Figure 14).
Figure 13: Power Warning Label
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