w_tom wrote:

Numerous points that make assumptions based in a world where
impedance does not exist - where only resistance exists.

First, nothing will stop a direct strike. But direct strikes
routinely do no damage when they are diverted. Major difference
between stopping (which plug-in protectors hope you will assume) and
diverting which is standard where direct lightning strikes do not
damage. Again, 25 direct strikes annually to electronics atop the
Empire State Building; 40 annually to the WTC - and electronics not
damaged. It is routine to earth direct strikes without damage -
because we don't stop a direct strike. We divert it to earth.

Inductive transients? Well put some numbers to them. I assume
this is about a nearby lightning strike to a long wire antenna. Well
that nearby strike may induce a few thousand volts onto that antenna.
Then we connect an NE-2 (neon glow lamp) from that antenna to earth.
Because that neon glow lamp conducts only milliamps, then that
thousands volts on antenna is now less than 60 volts. IOW induced
transients are that trivial. So trivial as to be made irrelevant by
protection inside all appliances. And yet, even industry standards of
30+ years ago (i.e. CBEMA) defined protection that was inside all
electronic appliances even that long ago. It takes so little to make
induced transients irrelevant. But it is the direct strike that causes
damage.

You did not see protector devices inside the blender? You were not
looking like an engineer? Why do you think wire was heavier gauge than
necessary? You are making a classic mistake. You have assumed
protector is as specific device. Protection is not necessary achieved
by a protector. Protection is something in the engineering. You are
instead looking for a specific device rather than first learning the
design. Meanwhile, we were discussing electronics appliances - not
blenders that have no electronics.

Is "drive to the off hook relay ... also not electrically connected
to the line, nor is most of the rest of the modem"? First go to data
sheets. That coil inside a modem off hook relay does electrically
connect to its wiper as those datasheets demonstrate. Not at 100
volts. But then even floors and wall paints become conductive during
these transients. Datasheet for that off-hook relay even states what
voltage causes a coil to connect to relay wiper. That is how modems
are so often damaged - as we also demonstrated when constructing
massive relay switching drawers in test equipment to connect and
disconnect those voltages. How are modems damaged? Get those
datasheets. Even optocouplers have breakdown voltages. When that
off-hook relay coil breakdown voltage is exceeded, then a destructive
transient passes through PNP transistor, through relay, and to earth
ground via phone line. Everything has a breakdown voltage. What we
assume is not conductive at trivial low voltages become a perfect
conductor at higher voltage.

Defined was how a modem is damaged when an AC electric line surge
finds earth ground via modems DAA section, phone line, and earthed
'whole house' protector.

Try to make two ends of a fluorescent lamp conduct with an ohm meter.
No connection. Then why do so few volts conduct current across that
tube when tube is glowing? Same principle. That relay coil and relay
wiper are electrically connected during a surge which is why we so
routinely repaired modems by replacing a surge damaged PNP driver
transistor. Surge incoming on AC lines and outgoing on phone line. To
be damage, electronics must have both an incoming and outgoing path.
Surges do not enter on phone line, ignore phone line 'whole house'
protector, crash on a modem, and stop. Electricity just does not work
that way.

As described in another post is wire impedance. Using Bud's
citations that demonstrate how plug-in protectors can fail to provide
protection: two TVs sharing a plug-in protector are at 8000 volts.
How can this be when those plug-in protectors are grounded by three
prong electrical connection to breaker box? Because one end of that
safety ground wire is at near zero volts and the other end is at 8000
volts - wire impedance. How can one end of a wire be at 8000 volts and
the other end at near zero volts? Welcome to a basic electrical
principle that also explains why different parts of a transmitting
antenna wire are at different voltages.

A 50 foot AC electric ground wire is maybe 0.2 ohms resistance. But
that same ground wire is maybe 120 ohms impedance to a surge. A
trivial 100 amp surge enters wall receptacle. 120 ohms times 100 amps
is a voltage somewhere below 12,000 volts. Same reason why those two
TVs can be at 8000 volts during a surge. Same reason why earthing must
be 'less than 10 feet' to single point earth ground. But then this is
old and well proven concepts - wire impedance.

More reasons why that 50 foot AC electric wire has even higher
impedance and creates other surge related problems. Sharp bends.
Splices. Bundled with other wires thereby induced transients on those
other wires. Wall receptacle is not an earth ground. Wall receptacle
is a safety ground. Wire impedance is why that wall receptacle is not
sufficient for earthing.

Yes appliances do have internal protection as required by industry
standards. Once some appliances (ie Apple II) installed those
protectors. No longer. MOVs inside the computer were as not effective
as they would be on its power cord - for so many reasons - including
too far from earth ground.

You have not seen MOVs vaporize? Get 30+ years experience with this
technology to see it. Some vaporized MOVs looked ominously ghostly.
Only left were two leads. Nothing left of its carbon material or red
paint.

Meanwhile, learn what joules really mean in a plug-in protector.
1000 joules in a plug-in protector is maybe equivalent to a 333 joule
'whole house' protector. And that assumes none of those joules are
used on other ports such as telephone or cable. Furthermore, as
joules increase, then protector life expectancy increases
exponentially. To be equivalent to a minimal 1000 joule 'whole house'
protector, the plug-in protector must be at least 3000 joules. Too
often, UPSes and power strips were only 345 or 900 joules - grossly
undersized. Only recently have some plug-in protectors sold 'still
too small' 2000 joules products.

You have never seen a grossly undersized protector vaporize? View
what was too unacceptably common with so many plug-in protectors:
http://www.ehs.washington.edu/LabSaf/surge.htm
http://www.westwhitelandfire.com/Art...Protectors.pdf
http://www.hanford.gov/rl/?page=556&parent=554
Imagine what these would do in dust balls on a rug behind the table or
on a desktop covered in papers. Does not matter if your desktop does
not have papers. Other's do which is but another reason why plug-in
protectors can also cause human safety problems.

But again, some principles to grasp before understanding surge
protection. Ever touch a doorknob to cause a static discharge? What
was the electrical connection from that finger to charges below your
shoes? Notice how many of those items are normally not considered
conductive. And yet electricity flowed from that finger tip, through
door, through floor to bottom of your shoes. Welcome to surge
protection where concrete and linoleum become excellent conductors of
electricity. Where a coil and wiper inside a relay become electrically
connected. Just more examples of why surges cannot be stopped - and
therefore why effective protection has always been about diverting
before a surge can enter a building. Diverting via low impedance - not
just low resistance - connections to a single point electrode.

One final point. Single point need not be a single ground rod.
Single point can also be a halo or ufer ground completely enclosing a
building's perimeter. But single point earthing and low impedance
connections are essential to effective protection.


You sure do like to babble, too bad 99.9% of what you say is either
total nonsense, pseudo-science, or hopelessly misapplied scientific
principles. Your links to claimed "vaporized" MOVs show no such thing
either.

Pete C.