Daktronics AF-3150-20-R,A - Manual (Page 26)

Proper power installation is imperative for proper display operation. The following
sub-sections give details of display power installation.
Grounding
This display is intended to be installed in accordance with the requirements of
Article 600 of the National Electrical Code and/or other applicable local codes.
This includes proper grounding and bonding of the display.
Displays must be grounded according to the provisions outlined in Article 250 of the
National Electrical Code
®
. Daktronics requires a resistance to ground of 10 ohms or
less.
The display system must be connected to earth-ground. Proper grounding is
necessary for reliable equipment operation. It also protects the equipment from
damage from electrical disturbances and lightning. The display must be properly
grounded or the warranty will be void.
Figure 19: Display Grounding
The material of an earth-ground electrode differs from region to region, and from
conditions present at the 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
in earth, the steel is either primed or it corrodes, making it a poor ground.
A minimum of one grounding electrode must be installed for each display face. The
grounding electrode is typically one grounding rod for each display face. Other
grounding electrodes as described in Article 250 of the National Electric Code may
be used. Daktronics requires that the resistance to ground be 10 ohms or less. If the
resistance to ground in higher than 10 ohms, it will be necessary to install additional
grounding electrodes to reduce the resistance. The grounding electrode should be
installed within 25 feet of the base of the display. The grounding electrode must be
connected to the ground terminal in the display panel board.
Electrical Installation 3-6