Name: Gordon
Status: Student
Grade: Other
Location: FL
Country: United States
Date: Winter 2009-2010
Question:
As wildland (forest) firefighters, we are commonly
taught that heavy smoke around high-voltage lines can hasten
'arc to ground' due to the carbon in the smoke. A less-common
theory that is making the ways through our community is that
heat (air temp.) not smoke determines the likelihood of a
high-voltage line arcing to ground. Is there any validity to
either/both of these theories?
Replies:
Hi Gordon,
I suspect the reason is neither of the theories you have
suggested. I really doubt that the carbon particles in smoke
makes any difference since there would seem to not be enough of
them (compared to the amount of air molecules) to increase the
conductivity of the air. Also, the temperature increase you
refer to will not make any significant difference unless the
voltage was high enough, and the high voltage line was close
enough to ground, that it was almost ready to arc before the
smoke surrounded it.
I suspect the real cause could be the ionized particles in smoke
that might trigger a flashover. But even then, I wonder how much
of this problem is fact, and how much is unsubstantiated urban
legend.
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