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Re: [TCML] DANGER Ground wire question (Need a straight answer)
Dex Dexter wrote:
Yes I was concerned about this,but I know the local instalations
conditions, and give a good thought before doing such grounding.I am
sure about safety issue. Nobody in my neighborhood can or will be
hurt by my coil.Cold water pipes are much bigger,better, and safer
grounding than any counterpoise in my case.
I find that hard to believe:
1) cold water pipes are basically like wires about 1" in diameter
2) water pipes are sometimes made of not so great RF conductors like
steel/iron and plastic
3) cold water pipes are connected to things that people touch
4) cold water pipes are hidden inside walls and under floors, so if
there is a problem with arcing, it's in a place where you can't see it.
Granted, you could be living somewhere with known copper piping that
goes underground (and doesn't have an insulating barrier between pipe
and soil).
these are just some of the reasons the National Electrical Code
doesn't allow cold water pipes to be used as a ground anymore.
However,if you are interested THERE is a small voltage built on the
water pipe when the coil operates.Probably you are familiar with
voltage tester screwdrivers: http://en.wikipedia.org/wiki/Test_light
10 feet away from the coil it remains dark,but when water pipe is
tested by the instrument a weak glimmering light appears. This means
the presence of potential. But potential without current means
nothing. The power is important and my coil is a low powered one
(power input max 120 VA). When I touch the pipe my fingers dissipates
surely less than a miliwatt of RF power.
Surely? I doubt you have a calibrated fingertip, and for reasons
discussed in the archives, you won't necessarily feel RF burns until
it's to late (the frequency is above the "low pass cutoff" of your nerves).
And, as others have pointed out, one of the hazards is not the RF, but
that an RF streamer will provide a conductive path from primary HV at
line frequency to your "ground".
Besides that, it's the whole "get into good HV habits" thing. Today
you're working with a 100W coil, and you can make mistakes and live to
write about it. Tomorrow or next week, or next year, you may be working
at kilowatts, and that bad habit or practice you adopted will raise the
number of known TC deaths to 4.
A wise old HV guy (and that's a good combination.. you want advice from
*old* HV guys) told me that the first thing you should do is get a
moderately HV Van deGraaff generator (like the Science First 14" one)..
and work with it for a while. You'll "feel" the fields, and you'll
inevitably get charged by induction or lean too close and take a hit.
And it stings. And you get respect for this kind of thing.
Interestingly, this weekend the snake vet told my daughter a similar
piece of advice about handling venomous snakes.. you need to be able to
handle a black racer (an agressive non-venomous species) for three
months and not get bit. Because each time that racer bit you, you just
died or went to the hospital. (He was explaining why he handled her
little 120 gram ball python the way he did..ingrained habits..)
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