On Sep 30, 11:24 am, Boden wrote:
bud-- wrote:
Nate Nagel wrote:

Does anyone make a plug in suppressor that has TWO coax connections?
I just realized that I was considering running both cable and an
antenna connection to each TV in my house, but all the surge strips
that I have everything connected to only have connections for one coax
(I guess they assumed that someone would have either cable or an
antenna but not both...)

Seems like someone should make one....

There are supposed to be modular assemblies where you can add the
elements necessary for what you have. (I have not seen them.)

A possible kludge would be to have a short coax on the suppressor "in"
side to a cable entry ground block with the cable source connected to
the other side of the ground block. Bolt another ground block to the 1st
ground block and run the antenna through it. The voltage on the center
conductor of the antenna is not limited when doing this.

I'm beginning to re-think how to protect equipment that I really care
about. Perhaps Permalloy boxes?

Several times in the past few years I have lost equipment due to a
proximate strike. The most recent was when I was looking out the
window and saw lightning hit the chimney of the house across the street.
Numerous brick were "vaporized" and my theater system, several
computers and some other stuff all went belly-up. I had protection
against conducted surges, what I didn't have was protection at each
device against inductively coupled energy. My guess is a few million
amps and a fraction of a turn, all on the load side of the surge
suppressor. ugh!

Boden


Only about 5% of lightning strikes are over 100,000 A. Few are over
200,000A (not that isn’t plenty).

According to NIST guide, US insurance information indicates equipment
most frequently damaged by lightning is
computers with a modem connection
TVs, VCRs and similar equipment (presumably with cable TV
connections).
All can be (and probably are) damaged by high voltages between power
and signal wires.

"Protection against conducted surges" is not described. If you have
just a service panel suppressor, the 'ground' wires from cable and
phone entry protectors to the ground at the power service has to be
short. An example of a 'ground' wire that is too long is in the IEEE
guide starting pdf page 40. A short wire prevents high voltages from
developing between power and signal wires at the service points.

The interior wiring can act as an antenna, either long wire or loop,
when the strike is very close. This sounds like what you are
suggesting. An example of a loop would be cable and power wires,
connected at the service points, with the open end of the loop
connected to a TV. A plug-in suppressor should protect against that.

As I wrote earlier, if you use a plug-in suppressor all wiring going
to a set of protected equipment has to go through the suppressor. That
includes in particular cable and phone wires.

There are other wires that can act as antennas for direct pickup. That
includes speaker and alarm wires. Pretty hard to protect. Your
Permalloy box would have to include the speakers. The manufacturer
should provide the protection.

--
bud--