Re: Isolation Transformer

*Gleep*

Doesn't anyone here one-point test their equipment? Clearly, anything
that passes through your bench should be fit for polite society when
done. The Isolation Transformer is the functional equivalent of a
seat-belt, not cure-all against stupidity or ignorance. So, if you let
out a piece of equipment without testing for a whole range of faults,
shame on you. But when the thing comes first to you, an isolation
transformer is a simple, common sense precaution to take against the
unknown.

One-Point tester: Little neon-tester that will glow if any dangerous
current (AC or DC) exists at the workpiece, or any exposed part of it,
or any internal piece that should not show potential. There are
available in a spread of voltages from as little as 12V to 440V. About
US$2 each at home depot. Unusual voltages as much as US$5 at electrical
supply houses.

If my equipment has a core-short, I will find it with either the above
means, or with a VOM test-to-ground from various points... mostly done
before _and_ after I do any work on the unit. One of the more
interesting tests is testing AC over DC... that is test for AC on what
should be a DC circuit... you might be surprised at what you find.

The point being that electricity is dangerous. And should be treated
with respect _always_. And should not be taken for granted ever. As
Reagan once said: Trust... but verify.

Don't get me started on Variacs (unless they are metered), or dim-bulb
testers... Unmetered variacs are worse than useless and potentially
dangerous. Dim-Bulb Testers cannot measure "at the edges"... and the
meters had better be able to measure as little as 3-4 watts accurately.
On the other hand, a properly metered variac can be incredibly useful
as a diagnostic and troubleshooting tool.

Peter Wieck
Wyncote, PA

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