Mast ground rework

When I moved here about eight years ago, I quickly installed a small mast and associated ground system for the station. The grounding of the mast itself for lightning protection was a temporary solution, and less temporary than planned. This article documents the rework.

GroundRod01Above is the temporary solution. A 2.4m copper clad ground rod was driven into the clay, and a couple of short 25mm^2 tails connected to the mast tube. The long term solution was to be tidier and allow the mower / brushcutter to be used to trim grass without fouling the earth rod or cables.

The plan is to cut to bent top of the earth rod, drive it below ground level, and make a new tail of 35mm^2 (#2) cable and Cadweld it to the ground rod.

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Above is the rework awaiting some steel top hat section to protect the PVC insulated cable from injury. The cable passes down into a diagonal hold in the concrete foundation into the valve box to the right where the thermite welded connection can be easily inspected.

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Above is a view into the valve box of the Cadweld termination of tail to ground rod. The Cadweld used was a GT1161VPLUS, a OneshotPlus for two ports of 35mm^2 to 16mm ground rod. There is only one cable here so it is stripped and passed through the two ports. The picture is after the crucible is broken away, slag mostly removed, an irrigation valve box fitted and the hole back filled.

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Above is a close up view of a Cadweld of the conductor sizes used.

The ground resistance was measured using the three wire method. The groud rod consistently measures around 11.8Ω resistance indicating a soil resistivity of around 20Ωm (which is quite low).

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The grass is growing… slowly.