Daktronics Galaxy AF-3400 20 mm Monochrome/RGB Double-face Displays - Manual (Page 17)

Power Installation 9
3.4 Grounding
These displays are installed 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 within sight of or at the display.
The display system must be connected to earth-ground (Figure 6). 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.
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. If embedded in earth, the steel is either primed or it
corrodes, making it a poor ground.
• One grounding electrode for each display cabinet: One grounding rod is necessary for
each display cabinet. 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 6: Correct Grounding