On Thursday 24 January 2013 14:23 Robert Macy wrote in alt.home.repair:

On Jan 24, 3:07 am, Tim Watts wrote:
On Thursday 24 January 2013 08:05 nestork wrote in alt.home.repair:



I think that if there was good evidence that lightening rods DIDN'T
work, we would have heard about the controversy by now. If tall
building are all equipped with lightening rods, that's good enough
evidence for me to believe they do work.

Obviously, you want to ensure that you have a pretty massive cable to
transfer all of that current around the house and into the ground.
But, I'd rather fry a $300 cable than have lightening set my house on
fire.

I'd put one in if it wuz my house.

Cable?? The rods I've seen all use 1" x 1/4" (or roundabouts) solid
copper bar.

--
Tim Watts Personal Blog:http://www.dionic.net/tim/

"History will be kind to me for I intend to write it."

Thickness of the conductor is NOT to survive heating, but to maintain
LOW impedance during a strike. The sharp impulse of current is limited
by the self inductance [relating to diameter and shape of the
conductor] and the impedance [related to the cross sectional area]

Although a bar shape is probably the only available shape one can
easily get for the conductor, a round cross sectional area is the
best.

Good point - hadn't thought of that.

Just thinking about it, our flat roof at work in central London has not only
rods, but a load of the same copper bar running all over the roof cross
bonding bits of metal handrail (those roofs are a fire escape route
sometimes) and other misc bits of metal and ventilation ducts.

They are not leaving anything to chance - and this building is 4 floors
high!
--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"A fanatic is one who can't change his mind and won't change the subject."