Tesla Ground (RF vs AC)

From:  Gary Lau  22-Jan-1998 0830 [SMTP:lau-at-hdecad.ENET.dec-dot-com]
Sent:  Thursday, January 22, 1998 7:39 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: Tesla Ground (RF vs AC)

>> I have a couple more questions though. Should
>> I ground the case of my NST to my RF ground or the wall outlet ground?
>> I've heard of it being done either way, and I don't know which is best.

>The case of the NST should be grounded already through the third or
>grounding prong of your wall plug. This can be verified with an Ohm

Only true if the NST is used with it's built-in 3 wire AC cord.  You MUST
disconnect this since you DON'T want to connect to the AC ground prong.
Plus, one generally wants to wire the NST primary to EMI filters, PFC
caps, and a variac before pluging into an outlet, though most of these 
are optional.

>It should not be grounded to your rf ground because the voltage
>spikes and frequencies being shunted through that ground would be
>inductively coupled to the primary of the supply transformer, which
>would, in turn, inject the signals into the supply mains.

NO, NO, NO!  The NST case should be connected to the RF ground.  Same
with anything else likely to be struck with a secondary strike.  The high
frequencies involved in a Tesla coil stand no chance of being inductively
coupled from secondary to primary.  Additionally, the case should be
connected to one side of the safety gaps to each HV secondary bushing.
When the safety gaps fire, they are shunting high voltage, high frequency
energy away from your delicate secondaries.  You want this energy
channeled to a solid earth ground by the shortest route possible, not
traveling first through your walls and every appliance en route.

Gary Lau
Waltham, MA USA