On 1/24/2013 8:50 PM, Red wrote:

Another point though is discussion of the charge conductor - solid or
cable. Electrical charges travel on the surface of the conductor, not
through the center. A cable has multiple strands, each strand with
it's own surface. So a stranded cable provides more surface area&
more electrical discharge than a solid copper wire.

I agree with Robert Macy.

I believe hams like flat braid (like a flat stranded wire) for
conductors that may carry high lighting currents.


Another point is the roof lightning rods. The protection provided is
a 45 degree downward cone from each rod. So height of the rods above
the roof is important - short ones give very little surface area
protection whereas multiple higher ones can protect most of the roof.


Far as I know, the current design technique is to roll a sphere with a
radius of 30m over the building and surroundings. The sphere stays on
top of the rods. If the sphere touches the building, lightning can
strike there.

You likely need fewer rods with the sphere design than the cone design.
But if you transport the Empire State building to the middle of
Nebraska, with no surrounding buildings, lightning can hit the side of
the building. Sides of buildings may also need lighting protection.