I have done a couple of towers in my time now and found that the best way of
ensuring reliable ground is to build a cage out of copper piping or rods
insulating the copper outer cage from the steel rebar and concrete with
thick plastic sheeting. When pouring the concrete the weight of it will push
the copper cage into the surrounding ground.
The metal base of the tower shouldwhen be connected to the copper cage thick
braided cable, your ground radials can also be connected to the copper cage.
Another thing that you need to do is to "balance" your power outlet
grounding system to the copper cage, again with thick braided cable.
Living in a very high lightning area with my tower at 30m this system
proved thus far successful. None of the towers that was fitted with the
mentioned grounding system suffered from a strike nor was any equipment lost
due to statics.
I would suggest not to trust the rebar alone in the concrete alone.
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