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Re: Grounding of HV Transformer.

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Chris,

Tesla list wrote:

Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>


I know this seems to have been widely discussed before,
but I have a different setup from most other coilers I think.

I use a home wound transformer which has one side of the
secondary connected to the core and grounded to mains
ground. I connected it this was, because neither the pri
nor the sec have substantial amount of insulation from the
core ( I kept so original pri and would my own secondary )

To clear things up, here you can see some pics of the


I know this is mega-strayfield and far from ideal, but
it was what I had on hand and could manage to wind.
The xformer is mounted insider a metal can which is
floating but can be grounded.

The problem is, whenever I get a primary strike the
HF burst makes all its way back to the controller and to
my hand... not very ouch.... but ouch nevertheless..
I use line Filters between xfromer and variac which seem
to hold up well under normal conditions, but these spikes
are just getting through, sometimes causing LV wiring to
arc to mains ground ( controller case ) over a distance of
1 inch or so which causes a bad short and tripping breakers.

I derive HV between mains ground and the HV Terminal and
have the RSG and safety gap across the two. Should I change
anything, maybe connect the cap across the xformer thus
tying the inner end of L1 to ground to achieve better voltage
standoff? I tried this once but instead of reducing arcover it
increased, but this was only a short test for obvious reasons.

Any suggestions appreciated!


Christoph Bohr

Looks pretty cool! If your using mains ground and have no RF ground, then every time you get a primary strike (or even when the current gets high), you can certainly be zapped. You need a dedicated ground for RF. Tie the core (sec) to RF ground. Your inner primary and bottom secondary should also be tied to RF ground. This will help keep the spikes off of mains ground and will reduce your shocking experience. Don't change your cap configuration. It's set up ok as is.

Take care,