RE: Ground - where should it stop?

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>

You ask a very good question, and I'm not sure there is a consensus.

Most of the circuits I've seen, including my own coil, have the mains
ground going only as far as the variac case.  The NST case is connected
to the RF ground, as is the middle electrode of the safety gap and
bypass caps, and secondary base.  

In a thread a couple of months ago, Malcolm Watts mentioned that he
connects his NST case to the mains ground, and for a good reason.  No RF
ground is perfect.  There will be some very high voltage noise present
between the RF ground and the mains ground.  If your NST case is at RF
ground and your NST primary is ar mains ground (ons side is neutral,
same as ground), then this high voltage noise will be trying to break
down your NST primary-to-core insulation.  I can't say though that I've
ever heard of this taking out an NST.  I'm not sure how such a failure
would manifest itself.  

If the NST case is connected to the RF ground, then it's very important
to use an EMI filter between the NST primary and variac.  I added a page
to my web site explaining the importance of hooking up an EMI filter in
the correct direction.  See
http://people.ne.mediaone-dot-net/lau/tesla/emifilter.htm

One problem with a mains-grounded NST case is that should a streamer
strike the primary circuit, it would be directly coupled to the mains
ground.  Malcolm pointed out that he's taken precautions to prevent
primary strikes.

I'm not sure the issue is settled.

Gary Lau
MA, USA


Original poster: "Matt S. by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<matt777777-at-hotmail-dot-com>

I have another question that I was hoping for some help with... (thanks
to 
all who responded to my lest one).
I have seen conflicting (to me) information on where to stop the house 
ground.
I am planning on running it (the house ground) up to my
variac/controller 
cabinet, and then I am unsure of whether to run it through the
(relatively 
long) cord to my NST(s) or not.  I will be grounding my secondary and
the 
center of my safety gap (and strike rail) to a (separate) RF ground
(buried 
Cu pipes)
---------so, my question is.... should the house ground be run to the
NST 
ground terminal on the input side or should it stop at the controller
cab. 
with the RF ground hooked up to the NST ground terminal?
(I am hoping to have my NSTs right under the primary  - i.e. in harm's
way 
sort of).
Thanks in advance - I have no doubt that this has been asked before, but

there are so many occurances of "ground" in the archives, it could take
days 
to find..(!)
Matt