Off the air!
Philip,
Yes, those guarantees are available on the better units. The Tripp-Lite
unit that I use has a similar guarantee. In general, these really
represent that the manufacturer has done a good enough job on the unit that
he's willing to absorb the cost of repair (or pay for the insurance policy
to do so) for the cases that the unit cannot absorb due to the intensity of
the strike. (and a bit of marketing – how many people do you know that can
plug $2 million worth of equipment in to a 6 outlet strip?) I'm not trying
to say that the units don't do a good job, but, with a close lightning
strike, it's just a question of a slightly longer time before the unit
blows.
Check out how many joules that your surge suppression device can absorb.
The better ones are around 300 joules, with the best ones being higher yet.
The cheap ones sometimes have ratings of 25 joules. Care to estimate the
energy contained in the average lightning strike? I have a lightning
arrestor installed on my panelboard, and use the Tripp-Lite Line
Stabilizer/Conditioner to feed surge suppressor outlet strips for my
system, due to the high lightning activity in the area where I live. I
also have additional protection on my telephone lines. I have no
illusions, though. If a strike hits close by, chances are I'm going to
lose equipment.
It's definitely worthwhile and recommended to take reasonable precautions,
but, if you want an absolute guarantee, it's just not available.
David