>> Has anybody had any experience with grounding towers with flat copper
strap v.s. using stranded wire or copper braid (tinned or untinned)? --jeff
Wb7aht
Hi Jeff,
I feel that wide copper strap is an excellent choice because of its low
impedance and outdoor durability. I used 3" x.032" copper strap from each
tower leg to tie into my ground loop. I drilled 1.125" holes in the strap
to fit over the anchor bolt to tower base connections (all crank-up towers
at my station). To make clean holes, I sandwiched the strap between two
scraps of plywood and used a forstner bit in a drill press. The copper
strap is dielectrically isolated from the galvanized base and bolts to
prevent galvanic corrosion using a pair of 1.125" ID stainless steel flat
washers at each connection. I also coated the connections with antioxidant
compound and it will be easy to check and service them periodically since
they are above grade bolted connections. I also use a separate piece of
strap to ground the copper bulkhead bar at the tower base. It is tied into
the ground loop with the shortest possible length.
The leg straps run the shortest path over the side of the concrete base then
drop below grade where they are silver soldered to a wire ground loop that
encircles the concrete foundation. There are four radial grounds that are
CAD welded to the ground loop at the four corners and these extend out
radially to about 50 ft each. There are 4' copper clad ground rods CAD
welded to the radials at about 8' intervals. The tops of the rods are
about 18" deep. I would have used 8' rods but I have really hard caliche
that starts at 18" deep and I just could not drive them any deeper even
using a full size jack hammer - so I cut the 8 footers in half and doubled
up the quantity at half the spacing.
I also use wide copper strap at the single point station ground panel to
connect to a similar ground loop at the station location.
Hope this info is of use to you & good luck on your project.
73
Matt
KM5VI
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