On Jul 15, 1:47 pm, Owen Duffy wrote:


I think that is flawed thinking.

Dunno.. Not if the ground connection itself is good enough..

A lighning down conductor needs to carry something like 20kA for 100ms, so
it needs to be substantial enough that it doesn't melt and remains in place
to protect against the next strike.

A #10 wire can handle that job if the ground connection is up to par.
Course, most real down conductor will be flat copper strap.
The rod or tube in the ground is not the down conductor per say,
although I guess you could consider it the end of it..
As far as DC contact with earth, it's possible the tubing could be
slightly better, as it's got surface both on the outside, and the
inside..
But I imagine RF flowing along tubing would mostly flow on the
outside,
rather than inside. But maybe a bit of both.. Not sure..
Copper tubing itself can easily handle any lightning strike. Way
overkill actually. If you had a well grounded copper tube lightning
rod, and it was struck, all you would see on the tip would be a tiny
arc spot, which might even be unnoticable unless you were looking
for it. Even a lowly #10 wire will barely raise temp when struck as
long as the connection to ground is real good. Of course, if it isn't,
it may well vaporize into blobs of metal..
MK