In article , jakdedert wrote:
larry moe 'n curly wrote:
Anthony Fremont wrote:
"larry moe 'n curly" wrote:

Why is it safe to use wood around high voltage when it contains
moisture?
Who said that it was?

Lots of people who tap circuit boards with wooden dowels to find
intermittent problems or who carve dowels to use as screwdrivers for
adjustments on CRT monitors or TVs that are running. So far, I've used
only plastic or fiberglass rods for this, but dowels are a lot easier
to buy locally.


Water in and of itself is a lousy conductor.

Water with the amount of carbonic acid formed by the amount of CO2
dissolved in it when it is in equilibrium with the atmosphere is not that
great an insulator!

Nobody ever said that wood was a perfect insulator, even dry...just 'good
enough'. If you're really curious, put your DVM probes on each end of a
hunk of wood and check.

If you can get a reading I'll be surprised.

Touch the tips of DVM probes with your fingers and see readings usually
in the megohms or 100's of K-ohms... Things are a little different when
you have hundreds of times more contact area - and skin form-fits to
contact a not-perfectly-smooth surface better than a piece of sheet metal
will. Try with two larger coins contacting a piece of wood when assisted
by small puddles of salt water - ohmmeter readings will usually be high
enough to indicate "no problem" but there is a problem with high
variability. And if you do a "study" on some sample set of a variety of
pieces of wood, there is the chance you will miss wood types or wood
sources that provide killer more-conductive wood, or you could fail to
include clunkers made more conductive by location, climate or past weather
or storage conditions or the like...

For tuning purposes, the utility of wood diddle sticks is their lack of
inductance, moreso than a lack of conductivity.

I think plastic diddle sticks have the same advantages. The
requirements here are lack of ferromagnetism and being no worse an
insulator than less-conductive core materials - many ferrite cores will
draw sparks/arcs if subjected to the output of neon sign transformers!

OTOH, the previous experiment should have demonstrated that there is no
danger in using them to tap out faults, either.

Danger there is negligible even if line voltages are present. I would
trust a piece of dowel rod from a hardware store to insulate me from 120V,
although I would not use it as a primary insulator in a mass-produced
product.

Just don't store them in a glass of water between uses. g

jak

- Don Klipstein )