[TowerTalk] Challenging Grounding/Bonding Situation ?

Matthew King - KK4CPS KK4CPS at gmail.com
Fri Sep 12 17:30:08 EDT 2014

Upon a cursory read, it sounds like you're doing it right - bonding all the
different grounding points together with your ground ring around the tower.

Let the Motorola R56 standard guide you.  It's the bible of this stuff and
is readily located with google.

Good luck with you installation!



On Fri, Sep 12, 2014 at 5:26 PM, N3AE <n3ae at comcast.net> wrote:

> I'd like to get the group's opinion on lightning protection for my new
> tower project. My property layout may be a bit different than most
> situations. I'll try to paint a picture.
> The tower base is 10 ft to the right (I'll call it "east") from the front
> of a detached garage. The garage has underground electric service (240vac).
> The garage load panel is tied to a ground rod on the side nearest the
> tower, which is about 9 ft away. The garage feeder's ground wire is bonded
> to this load panel and also tied to the ground bus in the house main
> service panel.
> The house itself is 75 feet "south" of the garage. The house main electric
> service panel (on another underground feeder from the utility) is on the
> opposite side of the house from the garage, about 145 feet straight line
> distance "south" of the garage and tower. The house service panel is tied
> to a ground rod at the feeder entry.
> In addition to the usual tower radial grounding scheme with multiple rods,
> I believe the tower radial system must be bonded to the nearby garage
> electric service ground rod, and I also need to run a separate #4 or larger
> copper wire underground from the tower (probably with more rods along the
> way) all the way back to the ground rod at the house electric service
> entrance. This would be about 180 ft of wire, keeping a gentle turning
> radius around the "southeast" end of the house. Near the tower, this wire
> run would be about 10 feet away from the garage power feeder for the first
> 75-80 ft.
> Coax and rotor lines will run in a PVC conduit either in the same trench
> as the bare #4 or a nearby trench. The shack coax entry panel will be mid
> way along the "east" wall of the house. In addition to ground rods there, I
> plan to tie the coax entrance panel into the #4 wire mentioned above.
> Anything wrong with this plan?
> My main concern is that electric feeder to the garage. The feeder enters
> the house basement on the "north" side and runs to the main service panel
> along the unfinished basement ceiling. Don't want lightning currents to
> prefer that route. The second concern is routing the coax conduit near the
> #4 bonding wire between the tower and house service panel. Possible
> inductive coupling during a lightning event?
> OBTW ... Up until now, I've just used wire antennas at this QTH, hung in
> the 80+ foot trees. When QRT, I always disconnect the feedlines (window
> line) and anchor the ends in the yard about 40 feet from the house. A few
> years ago one of the wire antennas took a direct strike. All the copper in
> the window line was vaporized and the antenna (a V-beam) fell to the
> ground. Had a foot deep crater in the yard where the window line was
> anchored. Nothing in the house suffered any ill effects except the cat, who
> hated thunderstorms ever since then.
> Thanks in advance.
> Shawn - N3AE
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