w_tom wrote:
On May 3, 4:38 am, Franc Zabkar wrote:
Can you elaborate on this by showing us the path taken by the strike
through the TV?

See many posts that describe this same failure to a network of
powered off computers. Surge incoming on wires that typically carry
most surges into buildings: black (hot) AC wire. Surge arrived two
plug-in protectors - each adjacent to powered off computers. Often
that surge is trivial; does not overwhelm protection inside a
computer's power supply. Maybe - but irrelevant due to the adjacent
protector.

Protector did its job - MOVs shunted (connected, diverted) surge
current into all other AC wires including the green safety ground
wire. Green wire connects directly to motherboard and network cards -
still seeking earth ground.

Path to earth was through the network and into a third computer.
Through that third computer's motherboard, through modem, and to earth
via phone lines. Semiconductors in these paths were damaged.

Any competent source (including the IEEE guide) along with any competent
manufacturer will tell you all interconnected equipment needs to be
connected to the same plug-in suppressor, or interconnecting wires need
to go through the suppressor. External connections, like phone, also
need to go through the suppressor. Connecting all wiring through the
suppressor prevents damaging voltages between wires going to the
protected equipment.

This is apparently way to complicated for w_ to understand.

For a more detailed explanation, read (starting pdf page 39) the IEEE
guide titled "Ground potential rise"
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf

The same section explains how plug-in suppressors work.


Plug-in protector is not for and does not claim to protect from this
typically destructive type of surge.

Complete nonsense. Just another of w_'s bizarre ideas.

But the same
ineffective protection is demonstrated in Bud's citation - 8000 volts
destructively on Page 42 Figure 8. That surge was permitted inside
the building. Plug-in protector did nothing to avert 8000 volts
destructively via the adjacent TV.

The illustration in the IEEE guide has a surge coming in on a cable
service. There are 2 TVs, one is on a plug-in suppressor. The plug-in
suppressor protects TV1, connected to it.

The point of the illustration for the IEEE is "to protect TV2, a second
multiport protector located at TV2 is required." Apparently a radical
idea for w_.

w_ says suppressors must only be at the service panel. In this example a
service panel protector would provide absolutely *NO* protection. The
problem is the wire connecting the cable entry block to the power
service 'ground' is too long. The IEEE guide says in that case "the only
effective way of protecting the equipment is to use a multiport protector."


What would have avoided above network damage? Homeowner later
installed and earthed a 'whole house' protector.

A power service suppressor is a real good idea. It does not protect
equipment connected to both power and signal wires if there is a high
voltage between those wires as in the example above. There are other
hazards that it also misses.

For independent advice read the IEEE or NIST guides. (Both say plug-in
suppressors are effective).

--
bud--