Daktronics DataTime DF-1012 Time & Temperature Display - Manual (Page 12)

8 Electrical Installation
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 site. Consult any electrical codes that apply.
• Support structure cannot be used as an earth-ground electrode: 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.
• One grounding electrode for each display face
3.4 Power Installation
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 paragraphs:
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 disconnect. The National Electrical Cod requires the use
of 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 Article 250-32 of the National
Electrical Code. If the installation in question meets all of the requirements of Article 250-32, 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.
3.5 Lightning Protection
Using a disconnect near the display to completely cut all current-carrying lines significantly protects the
circuits against lightning damage. For this system to provide protection, disconnect power when the display
is not in use.
Disconnect the DM-100 control console from power and from the signal J box when the system is not being
used. The same surges that may damage the display’s driver can also damage the DM-100 console’s circuitry.