Radio on 100 foot wire was a good example. But you
misunderstood what the example demonstrates. An earthed 100
foot wire does not short out radio reception AND acts as a
dipole antenna BECAUSE wire is not a perfect conductor. Wire
has impedance. Impedance is why signals on that 100 foot wire
are not shorted out - end to end. And that was the point.
Wire is electrically different at both ends. If wire was a
perfect conductor, then wire could not act as an antenna.

Radio signal captured at near 50 foot is not shorted out by
far 50 foot of wire because, and again, wire is not a perfect
conductor. Wire is electrically different at both ends.

Some here would rather insult than first learn these basic
facts. They should have first asked for clarification so that
they could learn. They 'assume' that 10 AWG power wire is
electrically equal at each end - which is enough justification
to insult? If true, then joining neutral and ground together
in a wall receptacle would be perfectly acceptable. Then we
need only run one wire back to breaker box - not a separate
white and green wire. We intentionally run two wires from
same point inside breaker box to receptacle because wire is
not a perfect conductor.

Even though both white and green are connected together in
breaker box, they are electrically different at their other
ends. Why? Because all wire has electronic characteristics
as the 100 foot radio wire demonstrates; as a single point
ground to stop hum between audio components demonstrates; as
separated chassis and motherboard grounds makes a computer
resistant to static electric problems.

Wire has tiny resistance and impedance. Wall receptacle end
of a white wire is not electrically same as other end in
breaker box. And all grounds, even though interconnected, are
quite different as explained in that earlier post.

Outlet receptacle ground is a human safety ground. From the
perspective of radio waves that we call surges, that outlet
safety ground is all but disconnected from earth ground. IOW
outlet safety ground is not earth ground. Breaker box ground
may or may not be earth ground depending on electrical
characteristics of the earth ground wire - ie length, number
of sharp bends, etc.

Wire is always considered electrically different at both
ends. Even when wiring a house that meets NEC requirements;
code is written knowing that wire is not electrically same at
both ends. Those who insult should first learn these basic
electrical principles; why grounds in different locations
serve different tasks; and how wire works.

Mike wrote:
w_tom wrote in :
Example - we earth ground a radio antenna input directly at
the radio - well less than 1 foot of wire. Radio reception is
severely diminished. We then ground same antenna input with
100 foot wire connected to same ground. Suddenly radio gets
excellent reception. Why? If wire is the perfect conductor
as so many wish, then that 100 foot wire to ground should have
also eliminated radio reception. Therein lies the reason why
so many grounds are different. They are all separated by
electronic components - ie. wire.


Bad example, and incorrect.

The 100' wire to ground would actually be used as one part of a
dipole antenna, therefore increasing the antennas signal capturing
ability. The 1' ground (because of it's short length and difference
in length to the other side of the antenna lead) would basically
shut down the antennas' ability to capture a signal.