Daktronics CH-1421V - Manual (Page 10)

Installation 2-4
The steel support structure for the display cannot be used as grounding. The support
is generally imbedded in concrete, and if in earth, the steel is either primed or it
corrodes making it a poor ground. Use one ground rod at each scoreboard support
column.
The National Electrical Code requires the use of lockable power disconnect near the
display. Provide a lockable disconnect switch (knife switch) at the display location so
that all power lines can be completely disconnected. Use a 3-conductor disconnect so
that both hot lines and the neutral can all be disconnected. This is important in
protecting the display against lightning.
There are two considerations for power installation, New Power Installation and
Existing Power Installation. These two power installations differ slightly, as
described below.
New Power Installation: The power cable must contain a separate earth-ground
conductor. When a separate ground conductor is used, do not connect neutral to
ground at the disconnect or at the display. To do so would violate electrical codes and
void the warranty. Refer to Drawing A-45220.
Existing Power Installation: When a separate ground conductor is not available,
connect the neutral to the earth-ground at the disconnect. Refer to Drawing A-45220.