[TowerTalk] What's a "Good Grounding System"??

[Bob Otto]

Hello Jerry,

Place about 20' of #8 wire coiled up horizontally about 3" from the
bottom of the concrete in the hole -- attach this to a ground rod in
the bottom of the hole.  This is a Ufer ground.

Place one ground on each tower leg.  Use #4 copper wire from each
ground clamp, extending 8' to an 8' copper clad ground rod.  Make sure
that there is no less than 16' between ground rods.  Also make sure
that the ground wires do not have a radius less than 2', and that the
clamp on the tower leg is well ABOVE the clamp to the ground rod.  In
other words, make sure that the path from the tower has no sharp radii
and that the direction of travel is always easily DOWN, not horizontal
or up.  I like to coat the actual connection of the #4 wire and the
ground clamp screw with GE silicone to insure that there is no
corrosion or dirt over time.  Be sure you tighten the ground clamp
screw very tightly, perhaps "mashing" the copper wire a bit to make
sure you have a really good connection.  I've even used channel locks
to flatten the copper wire a bit before making the connection.

If it's possible, attach the ground wire from all shack equipment to a
ground buss, and use the same rules for taking a line from the ground
buss out of the shack to a ground rod, preferably one the tower ground
rods.  I personally use #4 copper wire from a ground buss or bar made
of 1/4" x 1" solid copper.  I drill holes in the bar every 3" for
bolts and bolt (using wing nuts for easy connections) each #12
multistrand wire to a piece of equipment.  I even ground switches
separately, drilling and bolting if there are no ground connections on
the switch as manufactured.

It's also a good idea to use a ground buss for all your antenna &
rotor cable connections, grounding the buss with #4 copper wire as
well.

Please note, all #4 copper wire is SOLID COPPER, not multistrand
wire.

Fore much better descriptions, see the Polyphaser manual on grounding
at http://www.polyphaser.com/

Hope this helps.

73's from.......

Bob Otto
N8NGA@one.net
Cincinnati, Ohio

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Thursday, October 26, 2000, 10:03:28 PM, you wrote:

JK> Bob, AA0CY/3 posted:   "
JK> Again, as has been emphasized by other posters, a good
JK> ground system (and of course there too there are differing
JK> opinions on what constitutes a good grounding system) is the
JK> most important aspect of lightning portection."

JK> Everyone probably already knows the basics... ground each chassis to a
JK> common station ground buss, turn the antenna switch to the "common"
JK> (grounded) center position when not in use or storms are in the area, tie
JK> the station ground and every other ground on the property to the service
JK> (AC) ground (usually the ground rod directly under the electric meter),
JK> stuff like that.
JK> (Maybe there's some disagreement with all that?) But this reflector concerns
JK> towers, so.....

JK> Assume a 60 foot tower on a big chunk of concrete with a rebar cage inside.
JK> Exactly what would constitute a "good ground".... or more particularly, a
JK> "good enough ground" to handle whatever lightning strike might hit the
JK> tower, and keep it from destroying anything...how many ground rods, how
JK> deep? Anything else? What about "lightning arrestors", "surge protectors",
JK> and the like.... any good?

JK> Jerry K3MGT







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