Re: [Phys-l] Chimp unsuccessfully hangs from high voltage line

[John Denker <jsd@av8n.com>]

Regarding electric fences, Matt Coia wrote:
> I'd equate it to getting zapped with 110v in a house.  It certainly gets
> your attention.

I would not make such an equation.  I would certainly not say anything
like that in front of students.

Fences are not 100% safe, and 110V wires are not 100% lethal, but if
you look at the probabilities, you will see that 110V wires are vastly
more dangerous ... even if you take unequal exposure factors into account.
The last CPSC figures I saw were something like 200 household electrocutions
per year (down from 700 per year in the 1970s).

Electric fences are designed so that touching them "should" be nonlethal
under all conditions.  The rules for 110V wires are completely different;
the design rule is that you "should" not touch them (without proper
insulation) under any conditions.

=============

Please, folks, let's get this one right.  This is one of the few topics
that comes up in physics class where misinformation can be directly
life-threatening.  (Another such topic is the physics of driving cars.)

There is much room for improvement.

  For example, in Sears, Zemansky, & Young there is a multi-page discussion
  of household wiring that is just appalling.  They evidently don't understand
  the distinction between "neutral" and "ground".  The wire that is functionally
  neutral is called ground, and is diagrammed as grounded in multiple places ...
  which would be unsafe, not to mention being in violation of code.

  They go on to give an incorrect description of how a GFCI works.

It's true that familiarity breeds contempt ... but that doesn't make it any less
dangerous.  110V wiring is not to be trifled with.  For those "lucky" enough to
live with 220V mains, this is even more important.