Daktronics BA-1518-11, Installation, Maintenance, And Specifications Manual

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Grounding
Displays MUST be grounded according to the provisions outlined in Article 250 of the
National Electrical Code and according to the specifications in this manual. Daktronics
recommends a resistance-to-ground of 10 ohms or less.
The electrical contractor who is performing the electrical installation can verify ground
resistance. Scoreboard Sales and Service personnel can also perform this service.
The display system must be connected to an earth electrode installed at the display. Proper
grounding is necessary for reliable equipment operation. It also protects the equipment from
damaging electrical disturbances and lightning.
The display must be properly grounded or the
warranty will be void. Refer to the schematic, Drawing A-156750 , for information on where to
connect the grounding wire. Connection at the duplex receptacle is illustrated in the lower section
of the drawing.
The material for an earth-ground electrode differs from region to region and may vary according
to conditions present at the scoreboard installation site. Consult the National Electrical Code and
any local electrical codes that may apply. The support structure of the display cannot be used as
an earth-ground electrode. The support is generally embedded in concrete, and if it is in earth, the
steel is usually primed or it corrodes, making it a poor ground in either case.
Branch Circuit Grounding
A grounding electrode at separate structures/displays will not be required where only one
branch circuit supplies the structure and branch circuit includes an equipment-grounding
conductor for grounding the non-current-carrying parts of all equipment.
Power Installation
There are two considerations for 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 subsections:
Installation with Ground and Neutral Conductors Provided
For this type of installation,
the power circuit
must
contain an isolated earth-
ground conductor. Under
this circumstance,
do not
connect neutral to ground at
the disconnect or at the
display.
This would violate
electrical codes and void the
warranty
. Use a disconnect
so that all hot lines and
neutral can be disconnected.
The National Electrical Code
requires the use of a lockable power disconnect within sight of or at the display.
Figure 4: Installation with Ground and Neutral Provided
Electrical Installation
7-2