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Re: [TCML] DANGER Ground wire question (Need a straight answer)



I don't have a calibrated fingertip but I
know the currents are very small.
RMS value  way below 0.5 mA.
That's not shock hazard at any frequency.
That's not conducting RF burn hazard too.
Some skin burn hazard would exist if the
peak voltages are sufficient for air breakdown
of a short finger-to-pipe gap to occur.
That doesn't happen.Nothing odd since
I determined  peak volts were less than 100 V .
I even tried  to see if I can create
small arc by making and breaking contact
between other electrode and the pipe.
And I couldn't.
Why is the water pipe mesh quite a  good RF
grounding at my place I am not sure.
They are not made of copper.That's for sure.

Having said all that I don't recommend this
way of grounding SGTC secondary!
With a high powered coil and under different 
circumstances it would be just asking for trouble.


Dex  

     
   
--- jimlux@xxxxxxxxxxxxx wrote:

From: jimlux <jimlux@xxxxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Subject: Re: [TCML] DANGER Ground wire question (Need a straight answer)
Date: Tue, 16 Feb 2010 06:41:02 -0800


> 
> 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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