On Oct 1, 5:45 pm, w_tom wrote:
On Sep 30, 12:24 pm, Boden wrote:

Several times in the past few years I have lost equipment due to a
proximate strike. The most recent was when I was looking out the
window and saw lightning hit the chimney of the house across the street..
Numerous brick were "vaporized" and my theater system, several
computers and some other stuff all went belly-up. I had protection
against conducted surges, what I didn't have was protection at each
device against inductively coupled energy.

Will lightning
take a 5 mile path across the sky to those charges? Of course not.
..
In fact it can. It is the strike "out of the blue [sky]".
..
Same applies to a house. If household earthing is not single point,
then a surge also could have risen up into your house. passed through
household appliances, then back into earth - just like the horse.
..
It is very unlikely a phone entry protector was not connected to the
power earthing system. It is a little more likely a cable entry
protector was not connected.
..
Can surges be induced using electromagnetic fields?
..
There was a very limited investigation of surge damage to equipment
that included an insurance company, and a utility. One of the cases
had several channels of a multichannel home audio amp that were
damaged by directly induced voltage on speaker lines from a near
strike.
..
The answer
starts with reviewing how all incoming utility wires in every incoming
cable are earthed before entering the building. For example, was your
cable earthed short to the same earthing electrode that is only 10
feet from the breaker box? All incoming utilities must connect to the
same earthing electrode before entering a building.
..
Not just the same electrode. The length of the 'ground' wire from the
phone/cable entry protector to the power system ground or common
bonding point must be minimized.

The IEEE guide has an example of a ‘ground’ wire that is too long
starting pdf page 40.
..
One utility
demonstrates how to correct earth grounds that would otherwise create
appliance damage:
http://www.cinergy.com/surge/ttip08.htm
..
“Preferred” is correct. “Right” is bad. “Wrong” is, amongst other
things, a code violation.

Many houses have the cable/phone entry points distant from the power
service, so a short wire connecting entry protectors to power system
ground is not possible. In that case, the IEEE guide says in the
example above "the only effective way of protecting the equipment is
to use a multiport protector."

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