w_tom wrote:

If one has the necessary background knowledge, then nothing
poted is contradictory.

Most of what you post is contradictory babble. The remainder is slander.

For example David Maynard still
insists that a wall receptacle is earth ground because he does
not even understand simple principles such as wire impedance,
adverse effects created by sharp wire bends and splices (wires
inside walls), induced transient effects on adjacent wires,
and what that earth ground function really accomplishes.

Another lie. What I explained to you is the voltage increase due to that
impedance is essentially irrelevant to protecting the device as long as all
incoming and outgoing lines are clamped to it, as there will be no
excessive voltage across any device terminals: the only thing that matters
to 'protecting' it.

You apparently can't grasp the basic electrical fact that if the device
sees no damaging voltage across any terminal it's connected to that it
matters not where it is with respect to 'earth', or else no aircraft
electrical system would ever work.

And I'd love to hear w-tom explain how his '3 meter ground path' is
absolutely essential to protecting an aircraft's electronics from lightning
induced surges.

For illustrative purposes, take a 3 terminal device. Terminal 1 is at 0
volts with respect to w-tom's precious 'earth', as is terminal 2 and 3
because we'll postulate a 'perfect' suppressor that has clamped the three
together. Everything going into and out of the device is as the same
potential, 'earth': it's 'protected'.

Now imagine terminal 1 is at 500 volts, with respect to w-tom's precious
'earth', as is terminal 2 and 3 because we'll postulate a 'perfect'
suppressor that has clamped the three together. Everything going into and
out of the device is as the same potential, 500 volts: it's 'protected'.
Not only is it 'protected' but it is seeing exactly the same situation as
the one clamped to 'earth': no voltage potential between any terminals.

The difference between our 'perfect' suppressor and the real world one is
that the three terminals will not be at the exact same potential, in either
example. They will, however, be within the clamping voltage of the
suppressor (again, in both cases) and as long as that clamp voltage is less
than the device's voltage tolerance then it is protected, in both cases.
And it matters not if this 3 terminal device is in your home, or in an
aircraft at 30,000 feet where w-tom's precious 'earth' is more than '3
meters' away.

What w-tom does is take conditions and criteria that DO matter to a 'whole
house' protector and then fallaciously claim that any device, of any type,
and under any condition not only works the same way but needs to meet the
same criteria.

A 'whole house' protector, by it's nature, is not located at the device(s)
being protected but at the service entry and the effective clamp voltage
that interior devices will see is the voltage between earth, because of
their (non existent, according to w-tom) earth connection in the wall plug
(and/or neutral), and the power rails coming into them. The clamp voltage,
that the interior devices will see is, then, the 'whole house' protector's
clamp voltage PLUS the ground bump caused by impedance in IT'S earth
connection.

I.E. For a 'lousy' ground in violation of w-tom's '3 meters'
in a (simplified) 'whole house' protector:

power -------------------------------------------------
| |
| interior
'whole house 500V clamp devices sees
protector' | 1000 volts
|500V bump |
|from lousy |
single tie |ground impedance |
point ------------------------------------------------
|
earth spike V local earth '0'

The 500V is only for illustration with the amount of the ground bump being
dependent on the wired ground impedance (why it should be SMALL) and the
magnitude of the surge.

That is wholly different than a 'local' protector:

power -----------------------------------------
|
---- interior
Plug-in device sees
clamp ---- 330 volts
|
|
surge current raises device |
single tie ground relative to earth |
point ----------------------------------------
|
earth spike V local earth '0'

Note that even though the device's 'earth ground' is much longer, and with
much higher impedance, than the above 'whole house' protector it only sees
a 'safe' 330 volts instead of the potentially damaging 1,000.

(In both examples, for simplicity's sake, the traditional utility arc gap
suppressors are not shown)

In another misapplication, w-tom perpetually claims that the local
protector is 'under sized' (as if they were all the same to begin with),
citing his 'whole house' protector as 'proof' of it. But, again, the two
situations are not equivalent.

The 'whole house' protector, by the nature of it's (necessary) location at
the input panel, has very little incoming wire impedance to limit the surge
and so must be robust enough to handle very high currents. The 'local'
protector, however, has significant wire impedance between it and the entry
point (in fact, it is this 'excessive' wire length that w-tom claims makes
the ground wire useless) to limit the magnitude of the current it must be
capable of carrying in order to survive.

w-tom's arbitrary claim that 'plug-in protectors' are 'under sized' is like
saying a 30 foot yacht is 'under sized' for carrying two persons and citing
the Queen Mary as 'proof' of it.


In
fact, he is a good myth purveyor for the plug-in surge
protector manufacturer. Insufficient basic electrical
knowledge and little appreciation for the *art* of earthing.

Good description of yourself.

David - first you confuse destructive transients with all
other (and irrelevant) transients.

Not in the least.

Even a light switch can
create a trivial transient - noise on a medium wave (AM)
radio. Does that noise heard by an AM radio damage
appliances? Of course not. But plug-in protector
manufacturer will even site that as a transient to claim
transients are created inside a buildling.

The word is "cite." And what you 'claim' some unknown manufacturer 'cites'
is irrelevant since the topic is the technology of it; not what some yahoo
may, or may not, have written. Not to mention I wouldn't give 2 cents for
it as you've already demonstrated that slander is your preferred means of
'discussion'


Only relevant transients are the destrutive type that occur
typically once every eight years. Why do all protectors -
even plug-in type - ignore all voltages below 330 volts (on
120 VAC service) and 500 volts (on 230 volt service)? Because
anything less is not a surge and is well below what any
appliance must withstand - even LED clocks. Why did LED
clocks not fail routinely? Because dstructive transient are
so rare and are not created daily or weekly inside the
building.

No one ever claimed "destructive transient" happen "daily or weekly."
That's nothing more than another one of your strawman babbles.

snip of w-tom's continuing misapplication


David Maynard wrote:

Here's what the 'dispute' is between w_tom and me, on this point.

He makes multiple, often contradictory, claims (whatever seems
'convenient' at the moment). He'll imply that surges from
sources other than lightning simply don't happen (some
statistics I've seen indicate that 80% of equipment damaging
surges are from sources other than lightning). Or he'll
claim that appliances (as if all are equivalent) are already
protected from them (an apparent contradiction with their
'non' existence in the first place). Or, when given a direct
example, will then make the '8 year' claim, which he then
mischaracterizes as "across the country" in an obvious
attempt to suggest '1 incident' per '8 years' occurs 'in
the whole U.S.'. He'll claim that if your LED clock hasn't
blow up yet then nothing ever will, regardless of what kind
of device it is. Or that since your LED clock hasn't blow up
then there could not possibly have ever been any surges, and
never will be.

It is those, and other, either mischaracterizations,
irrational assertions or, in some cases, flat out lies that
I dispute.

To which he will then claim I said some absurdity that was
never said nor implied. In this case, since I pointed out
that non lightning related surges can, and do, happen he
then claims (as above) that I said equipment damaging surges
happen "daily" (the reason I supposedly sit here "worried"
about them even though my "LED clock" still works rolling
eyes)

It is perhaps a flaw of mine that I have little tolerance
for liars, and especially when they try to shove them down
my throat.