Unbalanced systems that cause current to flow through the ground
can cause electrolysis on underground conductors: water mains and
gas mains, etc.
A fellow physics teacher told his wife about 'static electricity'
when she complained of getting shocked from the hot and cold faucets
in the kitchen sink. Then one damp morning he saw steam coming out
of the ground near the sink.
Tests showed the full line voltage across the faucets, thanks to
'plumbers putty' insulating the hot and cold pipes from each other,
and an improper ground system on a new house.
An ungrounded conductor can become charged by induction. A charged
cloud drifting overhead, not yet ready to produce a lightning strike
will attract an opposite charge. A conductor in this 'field' will
allow charges to flow upward, leaving an opposite charge behind.
This is a 'series' circuit, which _adds_ to the cloud's potential,
inviting a strike, even more so than a nearby lightning rod.
Grounding a system lets the charge dissipate. I have lost electrical
equipment from induced charge, without an actual strike. I have also
been shocked this way. *Ground it!*
It is my firm belief that Ben Franklin's kite was not struck by
lightning. He knew the effects of induced charge and made a safe
and proper test for it. Others repeating the experiment were not
as knowledgeable and were killed.
John Spradley, in Sylmar, CA