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<big>On 2014-05-01 16:14, John Johnson wrote:</big>
<blockquote cite="mid:5362AB0F.7030506@golden.net" type="cite"> <big>**
Almost nothing will protect against a direct lightning strike as the
energy to be dissipated is just too high. Typical protection circuits
are intended to protect against lightning induced voltages, i.e. those
voltages induced in conductors near a lightning strike and induced by
the rapidly changing magnetic field around the strike.</big><br>
</blockquote>
<br>
<big>On lightning and lightning induced surge voltages:<br>
In the days of dial-up (and expensive PC hardware) I preferred external
modems as I considered these to be sacrificial as compared to the PC.<br>
Inside of 10 years, I replaced 3 modems on my sister's PC when the
modems were bricked as a result of lightning induced surges during
storms.<br>
She lived in Waterloo near Weber and Marshall on a lot that backed onto
a park and where there large and high trees. And a high water table.<br>
<br>
I also replaced a couple of dial-up modems at my place until I went
DSL. I and still use a rental DSL modem for the same reason,
sacrificial protection.<br>
And, a few times, I have had the DSL modem replaced by the ISP after it
was bricked during a storm.*<br>
<br>
I also have a few trees in my area. And the phone lines through and
near these trees.<br>
<br>
I prefer to have the lightning induced voltages reduced by the external
equipment before the cabling brings the voltages into the box or router.<br>
<br>
* I know the cost of DSL modems has dropped over the years and that
replacement units can be had for much less cost than before.<br>
<br>
PS: In about 1978, I gained a healthy respect for lightning, having
been dispatched by my employer to travel to the Pembroke area to repair
a rural T1 carrier system that had been damaged by a lightning strike
in the area. I had to replace most of the circuit boards in the 2 metre
high rack mounted system as well as the backplanes. And then wirewrap
the interconnect.<br>
<br>
JohnJ</big>
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