RE: grounding NST's

["Tesla list" <tesla@xxxxxxxxxx>]

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

Using a Terry filter connected to green wire ground won't diminish the
RF that would appear on that ground, should there be a primary streamer
strike.  When the safety gap fires, you now have a direct path from the
struck primary to the green wire.  I know that Malcolm is another
advocate of using the green wire ground, and justifies the practice by
saying that he mounts the top load sufficiently high to make a primary
streamer strike unlikely.  But I don't feel confident that I can prevent
that.

A primary strike with a green wire ground to the NST & filter would
wreak unequivocal havoc on the green wire ground and anything unlucky
enough to be connected to it.  Far less certain is whether the NST
primary to core insulation might be breached due to the RF ground to
mains potential.  I've seen LOTS of primary strikes, but I'm not sure
I've ever heard of an NST primary-to-core breach.

Gary Lau
MA, USA

> Original poster: Steve Conner <steve@xxxxxxxxxxxx>
>
> Hi Q, all,
>
> Personally I believe that grounding a NST to RF ground is a bad-ish
> idea. The reason is that the incoming line voltage powering the NST
> is referred to green wire ground. Therefore, any RF voltage appering
> on the RF ground will also appear between the NST primary winding and
> the core, which might cause flashovers.
>
> I think it's better to connect the NST's ground terminal to green
> wire ground, and use a Terry filter or similar (also connected to
> green wire ground) for protection.
>
> Steve Conner
> http://www.scopeboy.com/
>
>