Re: PC dmaged by lightning
- From: "JohnO" <johno@!NOSPAM!heathkit.com>
- Date: Mon, 31 Jul 2006 16:23:15 -0400
I struggled whether to categorically take apart most of your points, or just
let it go and move on. I'll take the latter.
-John O
"w_tom" <w_tom1@xxxxxxx> wrote in message
news:1154371119.046193.149580@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
JohnO wrote:
Just one point though...how did the OP's computer fail without a return
path?
We don't have a complete description for that OP's event. We know
that electricity must have a complete circuit for current flow AND that
current flow is necessary for damage. For example, one outgoing path
can be table on a linoleum floor. Or wires draped behind computer on
baseboard heater. Potential outgoing paths are numerous once a
transient is permitted inside the building. Just another reason why
effective protection earths before transient gets into a building.
We know computer was connected to ADSL modem which in turn connects
to AC mains. AC mains are 'most often struck' utility wires since
those wires may even protect telephone and cable from direct strikes.
AC electric might be an incoming path. If computer was damaged, then
both an incoming and outgoing paths exist.
One can be surprised by an unexpected conductive path. For example,
early 1900 Ham radio operators would even disconnect antenna, put that
lead inside a mason jar, and still suffer damage. Damage stopped when
antenna lead was earthed - destructive circuit through electronics
eliminated.
Effective testing for protection does not exist. We install based
upon lessons learned by our peers - including what Franklin
demonstrated in 1752. Earth every incoming wire at the service
entrance. If damage results, search for a human error and correct that
earthing. Find electrical paths previously not recognized. Protection
is about earthing long before a transient gets near to a computer. A
most common path of incoming transients is AC electric - where a 'whole
house' protector is routinely missing and where earthing may be
woefully insufficient.
The outgoing path existed through that computer. But then if the
incoming path had been earthed where AC mains entered the building,
then damage would have been averted.
.
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