Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

"larry moe 'n curly" wrote in message
oups.com...
Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.


No

"larry moe 'n curly" wrote:
Why is it safe to use wood around high voltage when it contains
moisture?

Who said that it was?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

Wood is usually classified as an insulator, but don't bet your life on
it. ;-) I would imagine that's why you see glass (or whatever they're
made of now) insulators used even at relatively low voltages.

"Anthony Fremont" wrote in message
...

"larry moe 'n curly" wrote:
Why is it safe to use wood around high voltage when it contains
moisture?

Who said that it was?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

Wood is usually classified as an insulator, but don't bet your life on
it. ;-) I would imagine that's why you see glass (or whatever they're
made of now) insulators used even at relatively low voltages.


I used to climb up the utility pole to get on the garage roof to retrieve
things
as a child. I always was slightly shocked until my feet were off the
ground.
Then again, I did grow up 1 block from the Gulf of Mexico so the salt spray
and high humidity had much to do with the conduction through the wooden
pole.

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.

larry moe 'n curly spake thus:

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.

I wouldn't want to go poking with one of them thar things around a
flyback transformer, no siree Bob.


--
The only reason corrupt Republicans rule the roost in Washington
is because the corrupt Democrats can't muster any viable opposition.

Wood is not a reliable insulator for electrical devices! Especially for high
voltage, don't even try it!

--

JANA
_____


"larry moe 'n curly" wrote in message
oups.com...
Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

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. 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.

For tuning purposes, the utility of wood diddle sticks is their lack of
inductance, moreso than a lack of conductivity. OTOH, the previous
experiment should have demonstrated that there is no danger in using
them to tap out faults, either.

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

jak

David Nebenzahl wrote:

I wouldn't want to go poking with one of them thar things around a
flyback transformer, no siree Bob.

Wooden dowel = ok
Lead pencil, holding onto metal ring around eraser = NOT ok

Don't ask............

Look at the breadboards people built for their old high
voltage tube projects. They're varnished. It's not just
for looks -- it seals the moisture in.


larry moe 'n curly wrote:
Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

On 1 Feb 2006 17:39:09 -0800, "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.

Plastic chopsticks.

John

On 1 Feb 2006 15:02:33 -0800, "larry moe 'n curly"
wrote:

Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.

Cellulose is an insulator and what little moisture remains in the wood
is parked in insulating cells.

Like all insulators it has a breakdown rating of volts per mil
thickness (highly variable in the case of wood, for both species and
moisture content). I have no problem poking around a TV with a clean
dry stick to look for intermittent's, but a Tesla coil working at
100KV treats wood like it was a conductor or semiconductor.

Wood sealed with lacquer, wax or varnish will be safer than bare wood.
--

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CRaSH wrote:
David Nebenzahl wrote:

I wouldn't want to go poking with one of them thar things around a
flyback transformer, no siree Bob.


Wooden dowel = ok
Lead pencil, holding onto metal ring around eraser = NOT ok

Learning the difference without getting burned, pricelsss.

Ed


Don't ask............

In article .com, larry
moe 'n curly wrote:

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.

Cleaner, drier wood is good for insulating line voltages - well, maybe
not quite good enough for making products with wood as the main
insulation... I would not mass-produce products using wood to hold
bare wires with line voltage. That's something plastics and ceramics are
for!

I have found dowel rod from a hardware store to be a good insulator -
so far - although I would not bet my life that it will insulate me from
several KV or 10's of KV.

As for old lumber that was in a basement for the past how many months or
years? Sometimes a good insulator, sometimes not... Usually reads
megohms to open circuit if you touch ohmmeter probes to it, but your hand
has more contact area. Old lumber in the garage is worse if anything, let
alone lumber that has been stored outdoors...

As for brand-new lumber? I have seen a couple examples not do well with
a neon sign transformer. Some lumber is not as good an insulator as the
usual dowel rods.
The problem is high variability!

If should I ever have to work on a single live wire live with several
KV, I would not stand on wood, but on a plastic milk crate or a plastic
bucket. (Better still make a platform of a bunch tied together with nylon
or polypropylene or other "plastic" rope/twine, so if I have to make a
sudden maneuver to keep my footing I won't have to worry about getting my
hands away from the high voltage before stepping onto the ground!)

- Don Klipstein )

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 )

In article , Mike Berger wrote:
Look at the breadboards people built for their old high
voltage tube projects. They're varnished. It's not just
for looks -- it seals the moisture in.

Or out!

- Don Klipstein )

Don Klipstein wrote:
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!

Wood plated with gold is also a great conductor; but that wasn't the point.

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...

Also kind of beyond the point.
snip

jak
- Don Klipstein )

Recall that paper is basically wood, and paper has been used for over a
century as an insulator in transformers and capacitors. In capacitors
it's like a few thousandths of an inch for each 100 volts, so it's not
too bad.

So it's likely that DRY wood is a pretty good insulator.

Ancient_Hacker wrote:
Recall that paper is basically wood, and paper has been used for over a
century as an insulator in transformers and capacitors. In capacitors
it's like a few thousandths of an inch for each 100 volts, so it's not
too bad.

So it's likely that DRY wood is a pretty good insulator.

I have not seen paper capacitors that were just sheets of paper and
foil stacked or wound up. And I have dissected lots of capacitors.

Most paper capacitors are actually paper-oil capacitors, where a
highly refined tissue paper web acts as a spacer (similar to what the
spacers between the plates of a lead acid battery ), while the oil (or
wax) soaked into all the pores performs most of the dielectric
function. The paper is also vacuum dried as part of the process of
getting all the pores filled with the hydrocarbon filling. Any air
bubbles left unfilled would be places where the E-field would be
concentrated by the abrupt drop in permitivity, causing corona that
would degrade both the paper and the oil.

On 1 Feb 2006 15:02:33 -0800, "larry moe 'n curly"
wrote:

Why is it safe to use wood around high voltage when it contains
moisture?

According to www.woodbin.com/ref/wood/emc.htm , wood contains
approximately 2-15% moisture at room temperature.


Hi there.. Well, a little over 35 years ago, when I was a young man,
and had just gotten my Amateur Radio License, I didn't have the money
for a center insulator for my low frequency 40 meter dipole, So, I
built a "homemade" insulator out of fresh, new, woodstock that my dad
had around... I carefully put the dipole together, wrapping it with
your usual black tape, and it worked great! The SWR was 1.2 to 1, and
I was happy.. A few weeks later, after a few moderate rainfalls, my
SWR went sky high, for no reason! (At least, that I didn't know about
yet) When I finally thought I figured out what was happening, an old
timer agreed with my asessment of the problem, and, had pity on me,
and was nice in giving me a ceramic glass egg insulator, and all was
well after that.. As far as your question goes, especially with high
voltage (as opposed to 50 watts RF) I wouldn't trust wood for a HV
insulator no matter what you did to it! Stick with what you know
works, i.e., ceramic glass, teflon, and the many new HV insulation
techniques that have come about for reasons of saftey first, and THAT
is what counts, OM.. Best luck then! Anthony, WB8MLA