w_tom wrote:
Pulses are sums of numerous frequencies - numerous sine
waves. A pulse is not just a pulse. Like all waveforms, the
pulse is also a sum of various sine waves (of different
frequency, amplitude, and phase). IOW a pulse is not just a
pulse. A pulse is what happens when numerous sine waves (with
boundary conditions) are summed together.

You continue to confuse mathematical analysis with physical reality.


That is also true of lightning. Lightning is not some DC
pulse.

Define DC. Has there ever in the history of mankind been anything
that qualifies under your definition? Could there be? Would the
current flowing in a flashlight that's turned on, then off, be "DC?"

How do you account for the discussion at the Web page you cited earlier
of positive and negative lightning?

Lightning is AC electricity - at numerous radio
frequencies.

I was trying to be clear. Lighting is electricity. But the
electricity called lightning does create electromagnetic waves
that will be of same frequency.

Ground wires from any surge protector must avoid sharp
bends. As I have so often done, a published source:
US Army Training Manual 5-690
3.4 Lightning protection subsystem (p 46)
d.1(i) Installation of surge arresters is shown for
grounded and ungrounded service ... In order to prevent
introducing excessive inductance and resistance in the
transient path to the surge arrester, No. 4 AWG (minimum)
insulated stranded copper wire of the minimum feasible
length must be used to make the interconnection(s) unless
otherwise recommended and guaranteed by the manufacturer.
Also, the interconnecting wiring must not contain loops
or sharp bends. Otherwise, the response time of the surge
arrester will be delayed and a higher clamp voltage than
that of the surge arrester will be impressed across the
protected equipment, thus increasing the possibility of
damage. In the event a very fast transient should occur,
it is quite likely that the surge arrester would never
turn on, and all of the transient energy would be
dissipated by supposedly protected equipment.

Interesting. Since you didn't provide a Web cite for context, I had
to look for one. The closest I could find was this, at pages 77-80 +/-:

http://ccb.org/docs/DMMHNAV/419A2.pdf

It's clear why they say to avoid loops, since inductance in
the path could lead to the result they describe -- sharp bends less
so. Query how sharp a bend you can put in #2 (or even #4) wire, anyway.

It's also interesting (to me) that they separately fuse the surge
protectors. It seems to me a fuse could present more of a discontinuity
than a sharp bend, and could also contribute some potentially
significant resistance (relative to copper wire).

I never said the earthing wire for a lightning rod must not
be surrounded by a building's girders.

As I recall you did say it shouldn't have a coil around it. Girders
could comprise a series of shorted one turn coils.

I only said the
preferred method of routing that earthing wire is to keep it
outside the building. This for reasons beyond the scope of
this discussion which is impedance, the purpose of earthing,
and characteristics of a lightning pulse that makes it so
challenging.

snip

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