Daktronics AF-3700-34 RGB - Manual (Page 17)

Power Installation 11
3.4 Grounding
This sign is 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 sign.
Displays must be grounded according to the provisions outlined in Article 250 of
the National Electrical Code
®
.
Installation with Ground and Neutral Conductors Provided
These displays use installation with ground and neutral conductors provided. The power
cable 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 disconnect if the
disconnect is not located within sight of the display.
Proper grounding is necessary for
reliable equipment operation. It
also protects the equipment from
damaging electrical disturbances
and lightning. Daktronics requires
a resistance to ground of 10 ohms
or less. The display must be
properly grounded or the
warranty will be void.
Important points about grounding:
• Follow local and national codes: 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.
• Support structure cannot be used as an earth-ground electrode: The support is
generally embedded in concrete, and if embedded in earth, the steel is either primed
or it corrodes, making it a poor ground.
• One grounding electrode for each display face: The grounding electrode is typically
configured as one grounding rod for each display face. Grounding is connected
between sections by bonding jumpers. Other grounding electrodes as described in
Article 250 of the National Electric Code may be used.
• Resistance to ground 10 ohms or less: This is required by Daktronics for proper
display performance. If the resistance to ground is 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 lug on the back of the display
(Figure 13).
Figure 13: Correct Grounding