RE: grounding question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Hi Peter:

I'm not sure that I explained my point adequately.

I use the terms "counterpoise" and "RF ground" interchangeably, as the
thing that the secondary base connects to.

I wasn't suggesting placing a choke in series between a secondary base
and the RF ground.  Rather, I was suggesting adding a choke between the
(secondary base / RF ground) and the mains safety ground, to ground any
60 Hz fault condition.

I'm curious what other folks read for resistance between their RF
grounds and mains safety ground?

I agree that a Faraday cage should also be connected to the mains
ground, but a cage wasn't part of the original topic.

Regards, Gary Lau
MA, USA


> Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
>
> I wire my cage to my HV ground and to mains ground.  RF ground
> current with a good cage should be small .
> Using a RF choke completely disconnects the ground at TC frequencies
> and should never be used. Try it on a normal TC and see the sparks
> fly across it. Similarly a counterpoise is a partial cage only so
> still large currents to ground so shouldn't use a choke. An imperfect
> Faraday cage should have only small RF currents to ground but should
> still go somewhere otherwise there is a shock risk. The imperfect bit
> mainly arises from the way the HV is brought into the cage and
> filtering / voltage suppression at the point of entry.
> In summary, downunder opinion is that if using a cage then it should
> be grounded to HV ground and on to mains ground. Counterpoise and
> standard TC's need a good RF ground and should not be connected to
> mains unless tiny.
>
> Peter
> http://tesladownunder.com
>
> >Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
> >
> >I agree that a counterpoise would benefit by a connection through an
RF
> >choke to safety ground, to establish a path for fault currents.
> >
> >..... How to construct an RF choke between the RF and green-wire
> >grounds that can support a fault current and still isolate RF from
the
> >mains ground?  Trouble is, I'm unaware of any actual measurements of
the
> >magnitude of the RF transients that appear on our RF grounds.
> >
> >Regards, Gary Lau
> >MA, USA
> >
> >
> >
> > > Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
> > >
> > > At 12:49 PM 10/9/2006, you wrote:
> > > >Original poster: Mddeming@xxxxxxx
> > > >In a message dated 10/9/06 1:27:38 P.M. Eastern Daylight Time,
> > > >tesla@xxxxxxxxxx writes:
> > > >Original poster: John <guipenguin@xxxxxxxxx>
> > > >
> > > >If I cant drive a grounding rod for RF ground, what is this
counter
> > > >pose under the coil I hear people mention?
> > > >
> > > >Thanks,
> > > >
> > > >      John.
> > > >
> > > >Hi John,
> > > >
> > > >     A counterpoise is a type of "virtual ground". consisting of
> > > > foil, wire mesh (chicken wire etc.) or radial wires arranged in
a
> > > > daisy wheel at least as long and broad as the coil is high or
the
> > > > topload diameter, whichever is greater. This is placed
underneath
> > > > the unit with RF ground end of secondary attached to it. The
> > > > topload "sees this as ground and all works. A foil one is
cheapest
> > > > and easiest, but wastes somewhat more power in eddy currents.
> > > > Radial wires are the most efficient, but hardest to do and keep
> > > > straight. a large square or circle of wire mesh is a good
> > > > compromise. NOTE: During operation, the counterpoise is floating
at
> > > > unknown high potential with respect to earth ground. DO NOT
> >TOUCH!!!!!
> > >
> > >
> > > For the latter reason, the counterpoise SHOULD be connected to the
> > > "green wire" safety ground.  I'd use a RF Choke of some sort, just
to
> > > keep RF off the building safety ground.
>
>