[Elecraft] Re: bonding of various ground rods

[Stuart Rohre]

Lightning mitigation practices change as more research and knowledge is
gained of the medium of damage.

For example, years ago, they said (not so many years ago), to coil up coax
and rotor leads to form a cable choke as it left the tower if above ground
level, so that the lightning would tend to go in a straight line down the
tower leg.  The inductive reactance of the coil would prevent it from
turning the corner and following the coax or cable.

Now they say this could form a one winding transformer and induce high
voltage into the lines worse than if you only made a 90 degree turn with the
coax, etc.

They used to say do not ground to rebar in the tower base.  Now they say to
bond it to the ground rods as well.  Lightning is somewhat inexact Physics
because there are differing types of strokes, and the energy can vary over
very large orders of magnitude.
You may suffer thousands of amps or only hundreds.  A stroke may vaporize
some conductors, or it may only follow along a telephone wire as a bad
surge.

The National Electrical Code calls for all radio, AC, and telephone grounds
to be bonded to each other.  There is a good reason for this.   The copper
paths will have a difference of potential around the house from one ground
rod to another, but this will be far less than the difference of potential
thru the rock and dirt from one ground rod to another, and so all the
grounds should rise to some high voltage together rather than being at
differing potentials thru the earth such that you have surge currents or
differing voltages side flashing from one ground to another.

The best ground we can get here in a rocky, poor conductivity area is to run
a copper conductor circling the house, and bond all the other grounds to it.
It is buried (even in a shallow trench), to give more surface area for
charge dissipation.  The surface area is what you want --for the charge to
spread out.

The crowfoot grounds put on tower legs helps to promote the charge to reach
ground and not go all thru one tower leg, but to divide among the area of
multiple copper conductors into the earth.

You want to follow the National Electrical Code, which has had the bonding
requirement for many years.  That way, your insurance company cannot balk
saying there was an installation deficiency in case of your claim.
72, Stuart K5KVH