RE: Temporary RF Ground and Demonstrations . . .

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Ted,

On 29 Aug 2002, at 13:39, Tesla list wrote:

> Original poster: "Ted Rosenberg by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>
> 
> Malcolm: You mentioned using the support steel girders of this building for
> an RF ground. In the new haunted house, I did the same thing. The columns,
> of which there are many, are about 20 feet high and are sunk into the ground
> through the concrete slab. The coil worked well <until the Terry Filter died
> due to a shorted MOV>. However, I noticed that the colums were ALSO the
> ground for the AC mains. Conduit was grounded to it etc.
> 
> So, is that always safe?
> 
> It's so convenient. But should I be careful?
> Were the columns in your building also the AC ground?

Difficult to say. They can't have been too far removed impedance-wise 
if they weren't. The building and its base are huge. By providing 
discharge points around the coil that were connected to the secondary 
base, I more-or-less contained the energy to a closed loop most of 
the time. No problems existed and the setup only interfered with our 
competitors in that it drew a large audience away from the other 
stands within seconds of switching on :)  I'm not so sorry to say 
that NST Jacob's ladder exhibited by one crew just didn't hack it.

Regards,
malcolm