Daktronics Outdoor LED Scoreboards Installation - Manual (Page 21)

Electrical Installation 15
Grounding
The display must be properly grounded according to local and national codes or the warranty
will be void. Proper grounding is necessary for reliable equipment operation and protects the
equipment from damage due to electrical disturbances and lightning.
Daktronics recommends a resistance to ground of 10 ohms or less. The electrical contractor
performing the electrical installation can verify ground resistance. Daktronics Sales and
Service personnel can also provide this service.
The display system must be earth-ground. The material for an earth-ground electrode differs
from region to region and may vary according to conditions present at the site. Consult the
local and national electrical codes.
Daktronics does not recommend using the support structure as an earth-ground electrode;
concrete, primer, corrosion, and other factors make the support structure a poor ground.
Note: The support structure may be used as an earth-ground electrode only if designed to
do so. A qualified inspector must approve the support structure and grounding methods.
There are two types of 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. In this circumstance, do not connect neutral to ground at the disconnect or at the
display as this would violate electrical codes and void the warranty.
Use a disconnect so that all ungrounded lines can be disconnected. The local and national
codes may require using a lockable power disconnect within sight of or at the display.
Installation with Only a Neutral Conductor Provided
Installations where no grounding conductor is provided must comply with local and national
electrical codes. If the installation meets all requirements, observe the following guidelines:
 Connect the grounding electrode cable at the local disconnect, never at the display
driver/power enclosure.
 Use a disconnect that opens all of the ungrounded phase conductors.
Lightning Protection
The use of a disconnect near the scoreboard to completely cut all current-carrying lines
significantly protects the circuits against lightning damage. In order for this system to
provide protection, the power must be disconnected when the scoreboard is not in use.
The control console should also be disconnected from power and from the signal junction box
when the system is not in use. The same surges that may damage the scoreboard’s driver can
also damage the console’s circuitry.