Re: Experience with odd effects. -Reply
Mike Visser ( mikev@powerquality.co.za )
Wed, 30 Dec 1998 08:52:59 +0200
Just my two cents worth,
I work with lightning protection, grounding, and
surge protection for a living and can resonably
safely say that some of the oddities can be linked
to incorrect grounding and bonding practices. re
some problems, we know currents flow in the
ground, and that they occur for causes as yet
unexplained, though the most are manmade.
The bottom line is that you need a unipotential
platform ie: the mains earth wire bonding
electrical earth (bare wire) to an earth electrode
designed for the body of the ground specific to
the location. The earth electrode normally
consists of rods driven into the ground or copper
buried in excavated earth but I digress.
We in S africa must tie our water pipes to local
earth (they make good electrodes if metallic) and
then again at the geyser.
The creation of "ground loops" of over roughly
100m in mains circuitry can result in the most
spectacular energy liberations during lightning
events. In essence, the loop exhibits aerial
characterisitics that resonate with some or other
frequency during the lightning event resulting in
unusual phenomenon.
The house up the hill getting blown out can often
be the result of "voltage doubling" along the
powerline. Consider a surge (say about 5 times
nominal voltage or 1000V along a 220V line)
propogating along a piece of wire, the surge is
made up of consecutive sinusoidal wave forms.
When these reach the end of the line and there are
no arrestors to quench them, they must needs turn
around, you then have wave upon wave (2000V) or
doubling, giving rise to blown equipment with no
apparent cause.
ps. you can have a bolt from the blue (cloudless
lightning).
Research has been done on ball lightning, and it
has been created under laboratory conditions, the
most critical aspect for ball lightning
propogation is : no air movement.
I wish you all well in the new year and look
forward to the breakthrough.
Mike Visser