Re: Variac Safety

[John Denker <jsd@MONMOUTH.COM>]

At 11:37 AM 12/1/00 -0800, Leigh Palmer wrote:

> My warning about the dangers of the Variac are meant sincerely,

I never questioned Leigh's sincerity.

> despite John Denker's minimization of them.

Unless my outbox is lying to me, I never "minimized" the danger of fiddling
with the outputs of a variac.

I stand by my assertion that fiddling with the outputs of a variac is
marginally more dangerous than fiddling with the outputs of an extension cord.

I stand by my assertion that the danger is in the fiddling, not in the variac.

In case somebody took this to mean that fiddling with variac outputs is
safe because extension cords are safe, that is diametrically opposite to
what I was trying to say.  I never said both are safe;  I think my note
says rather clearly that both are dangerous.

Read my lips:  if you connect an extension cord to banana clips and start
fiddling, it is quite dangerous.  Such activity would not be tolerated in
any research lab I know of.  The OSHA inspector would have a meltdown, and
I can't say I'd blame him.  And then... doing it in a teaching lab in front
of unskilled students is beyond foolish.

Unless there is some tremendous upside (heretofore unmentioned), why would
anybody want to mess with this stuff?  What needs to be done that can't be
done with lower voltages and lower currents, in a properly enclosed chassis?
(Transformer isolation or GFCI may help somewhat, but it is not in itself
sufficient for safety, and does not, in the absence of a proper enclosure,
meet code.)

There are people who get paid to move live 110+ volt wires around (notably
utility company workers) but
  a) there are highly trained and very methodical;
  b) every once in a while one of them makes a mistake and is killed;
  c) they don't leave live circuits lying around where bystanders can get
at them.