On Friday, October 23, 2015 at 4:19:21 PM UTC-4, wrote:
On Fri, 23 Oct 2015 13:22:20 -0500, Muggles wrote:

On 10/23/2015 12:58 PM, Oren wrote:
On Fri, 23 Oct 2015 11:24:40 -0500, Muggles wrote:

You sure know a lot about this subject. Are you an electrician?

If westom is an electrician I would not hire him.

ok Just trying to make sense of the discussion.

An SPD saved my 50" Plasma TV. I lost an older one without an SPD.
The server at work was saved from a brownout surge on an APC battery
unit. I suspect nearby lightning caused a main board damage on my
refrigerator.

Maybe he can explain _why_ planes have no earth ground. My guess he
thinks every appliance needs a barn lightning rod with an electrode.
Or planes drag a chain behind it to earth ground, like fuel trucks.

Long time ago when I was still living my parents, lightning hit the big
oak tree in our front yard. We felt the electricity in the air about a
split second before it hit, but nothing in the house was damaged. Not
sure why, though, because we didn't use surge protectors for anything
back then.

The Oak tree took the direct hit and not much got into your electrical
supply. You likely didn't have much if any "solid state" equipment
back then either. Most "solid state" equipment used in homes today
runs on between 3.5 and 18 volts, with the switch-mode power supply -
and occaisionally just an old-school transformer/rectifier circuit,
connecting it to mains power.
If a surge "punches through" the isolation of the power supply in any
way and the voltage getting to those solid state devices (transistors,
CMOS logic chips, microprocessors etc) excedes their maximum operating
voltage, the device is "toast" and the equipment it is part of is
damaged..

Noit exactly true. Most devices can withstand short duration voltages
well above their max *operating* voltage and still not sustain damage.



Better equipment has more and more effective surge and overvoltage
protection, and quite often internal protection fuses are the only
casualty where on a cheaper piece of equipment the damage may be so
extensive it is not worth attempting to repair it.

Older electronic equipment (using tubes, etc) ran on higher voltages,
drew more current, so the components were more "robust" and generally
speaking were less subject to damage from surges - although a direct
lightning strike would usually do them grevious harm as well.


Fast forward 20 years, I'm living in my own house and the large sycamore
tree across the street was hit with lightning. It damaged 2 tv's and a
pc. The tv's and pc all had surge protectors, but were damaged, anyway.


Do you have underground electrical service? Not saying this is what
happened, but if the electrical cables run underground just beside the
street, and the roots of that sycamore grow down and around those
power cables, being hit by lightning MAY have "injected" a surge into
the otherwize well-protected underground power distribution grid. Or
the surge may have come in the internet/TV line and done the damage
without affecting the electrical system in any serious manner.

Or if you have "overhead" electrical service, the Sycamore may have
been a lot closer to the power wires than the old oak years ago, and
got a lot more voltage induced (or otherwize transferred) on the wire
by the strike

The most probative thing here is that the TVs and a PC are the only
things listed as damaged. Those are appliances that don't just have
a connection to AC, they are also connected to cable, phone, antenna,
etc. The first question is, did those other TV/PC connections run
through those plug-in surge protectors, ie, there were designed to also
protect coax, phone, etc and were connected that way? If not, there's
your answer.