Re: [TCML] DANGER Ground wire question

[jimlux <jimlux@xxxxxxxxxxxxx>]

Tim Wenzel wrote:
> I think this is somewhat related to the last string I chimed in on and 
> got shot down.  I am prepared to get corrected again on this one, but 
> would not be commenting if I thought otherwise.
>
> I believe the voltages in question would be based on point of 
> reference.  If I ohm out my ground rod with the reference of another 
> ground rod or the bottom of my secondary, with my coil running full or 
> shut down, it measures 0 Ohms.  When I measure voltage for the same 
> reference points under the same conditions, there is 0 Volts.
>
> So, when I touch the ground rod of my coil while it is running full out, 
> whether I am firmly grounded or not, I feel nothing because there is 
> nothing.  If you have a floating ground, vis-a-vis a counterpoise, which 
> is not grounded to mother earth there may well be a price to pay.
>
> If your ground is hot while your coil is running, you had better have it 
> isolated from your power grid through the use of filtering equipment.  
> But I think the wisest thing to do is make sure you reference earth 
> ground in all operations,  unless you are running your own power grid at 
> your house with an isolated grounding system.
>
> ----- Original Message ----- From: "Bert Hickman" <bert.hickman@xxxxxxxxxx>


the problem is the RF fields.  Even if the ground wire were at the same 
potential as "earth", you probably aren't, because you're going to be at 
some RF potential. When you touch the wire, RF current flows, and ouch.


It's also very difficult to have a truly zero impedance at 100kHz and 
higher. there's always some inductance which raises the impedance, and 
the voltage.  Granted, not a whole lot.  1 meter of wire has an 
inductance of about 1 microhenry, and at 100 kHz that's about 0.6 ohms 
(=2*pi*f*L)...

The actual current in the secondary is pretty small so you're not 
talking huge voltages.  But, spark currents are quite high (that is, 
when you get a spark, it's not the RF current flowing, but the 
capacitance of the top load discharging through the spark very quickly), 
and that can be fairly high.

However, the "shocks from the ground" problem are more likely due to YOU 
being at some elevated RF potential (just from the 100kV/meter fields 
around the coil).  Basically, you become part of a big capacitive 
voltage divider.
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla