[ale] there's Risk and there's Stupid

[Michael H. Warfield]

On Mon, 2009-04-20 at 11:05 -0400, Sean wrote:
> Question:

> We now live in a condo development and all the utilities are buried,
> specifically, phone, power, and cable. The nearest overhead, exposed
> utility line is more than 100 meters away. Does this fact in any
> meaningful way lessen my risk of having a large surge take out
> unprotected electronics (tvs, tuners, etc.) and protected ones for that
> matter? I know that really LARGE surges can blow right past a good UPC/
> surge protector.

	For what value of "meaningful way"?  We live in a subdivision with all
buried facilities.  I would guess we're a good couple hundred meters
from the nearest overhead wires - as the crow flies.  In terms of wire
distance underground, we're at least double that to the feeds coming
into the subdivision.  We've still taken several direct hits on the
property (trees) and you would be amazed at what magnetic induction can
do.

	Years ago I did a talk at AUUG on the first hit we took titled "Tale
from Ground Zero - Lightning!"  The EMP that hit the basement from that
hit was strong enough to blow chunks of concrete out of the floor and
magnetize all my metal work surfaces and cabinets.  Lost no hard drives
and lost no data but several computers (including the one standing where
the chunks of concrete blew) required new motherboards because of blown
PS/2 ports.  My stereo, upstairs, picked up induction so severe on the
speaker wires it vaporized copper traces in the power supply (I saw the
copper vapor "painted" on the inside of the cover.  The whole house
surge protector and a slew of UPS's and surge strips prevented the
damage from being worse.  Our neighbors also took damage from induction.

	The house itself has never been hit.  But we've had 4 hits on trees on
the property (after the last one, we had the remaining 17 pines REMOVED
preemptively).

	My previous house had overhead facilities.  Ice and falling trees
caused more havoc than lightening and I can't honestly say I had any
more or less "surges".  Does it help having underground facilities?
Maybe, a little.  Do you still need protection?  Most definitely and the
more the better.  Will something still get through?  Always possible.

	Advice...  Get good surge strips with 3 wire protection and that come
with an equipment guarantee for your expensive electronics.  Then file
your receipt and the guarantee information away.  Cheap insurance for
when something does get through.

> Just curious. The thought occurred last night while watching a piece of the
> Hawks playoff game and having the signal interrupted by "severe weather"
> warnings several times. (It was a blowout so I went to bed.) :)

> Sean

	Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
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