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CHAPTER SIX: G
T
he National Electrical Code (NEC) requires that
every antenna installation be grounded. Also
many areas have local antenna-grounding
codes. Be sure that you are familiar with all of the
grounding and other antenna regulations in your
area.
Grounding an antenna is not just the law, it is good
common sense. Because the antenna is usually the
highest point on the house, it is highly susceptible to
lightning strikes.
Grounding the Mast
The NEC requires that the antenna mast and mount
be grounded directly. No splices or connections are
allowed in the ground wire between the mast and the
ground rod.
First, attach one end of a No. 8 or No. 10 copper or
aluminum ground wire to the antenna mast (Figure
6-1). One of the bolts on the mount can be used as a
fastening point. Masts that are painted or coated
must have their coating scraped off around the area
where they contact the mount. This will ensure an
electrical connection between the mast and the
mount. It is vital to get a good, solid connection.
(Once the mast is attached to the mount, any scraped
off portion that is exposed should be recoated with
paint or other sealant.)
Next, run the ground wire to ground as directly as
possible. Standard wire staples can be used to secure
the ground wire against the side of the house. Avoid
making 90˚ or sharper turns with the ground wire. A
lightning charge has difficulty making such a turn and
therefore may discharge into the house. Make ground
wire bends as smooth and as gradual as possible.
The ground wire must be connected to a ground rod
(Figure 6-2). Water pipes or plumbing fixtures are not
acceptable. A good copper-coated steel ground rod
driven at least 3 feet into the ground is required.
Special clamps that provide a solid connection
between the ground wire and ground rod should be
used.
Grounding the Transmission Line
It is not just the height of an antenna that makes it
susceptible to lightning strikes. Antennas and trans-
mission line can accumulate static electrical charges
that also increase the changes of lightning hitting an
installation. To properly "draw off" this static elec-
tricity, a small device known as an antenna discharge
unit (Figure 6-3) must be included on the installation.
The antenna discharge unit (also called a "lightning
arrestor") is connected to the transmission line at a
point close to where the transmission line enters the
ROUNDING
Fig. 6-1. The correct method of connecting a ground wire
Fig. 6-2. The correct method of connecting a ground wire
Fig. 6-3. An antenna discharge unit with a ground wire attached.
house. One end of a ground wire is attached to the
discharge unit. The other end of the wire is connected
directly to the ground rod.
Installation of the antenna discharge unit is very easy,
and detailed instructions come with each unit.
An antenna installation is not adequately grounded
unless both a mast ground and an antenna discharge
unit are installed correctly.
P
ROCEDURES
to the antenna mast.
to a ground rod.
G
P
ROUNDING
ROCEDURES
19
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