Daktronics AF-3700-20 RGB - Manual (Page 21)

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
® .
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 if the disconnect is not located within sight of the display.
The display system must be connected to earth-ground as shown in Figure 14. 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.
Figure 14: Correct Grounding of Display
Important points about grounding:
• 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 14).
• 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.
Power Installation 11