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Re: Very Confused On Grounding

Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Dan,

I just realized that my description refered to a "filter" and a "EMI filter". The "filter" was meant to be the "Terry filter". Yes, I would tie the NST case, the strike rail, the TC secondary base to RF ground and make the Terry filter ground connection short and directly to the NST case. For this case, you need to treat the NST as a non safety device (case is not tied to safety ground). Hoping your EMI filter has a metal enclosure, I would tie this enclosure to safety ground. If it doesn't have a metal enclusure and no ground connection, it can't have any Y cap filtering to safety ground and it wont be as effective of a filter. You may want to find a filter that does have a metal enclosure.

BTW, you will get different opinions from other members on tying the NST case to RF ground vs safety ground and will have to weigh the various tradeoffs for yourself.

Gerry R


Original poster: "Daniel Koll" <dk_spl_audio@xxxxxxxxxxx>

I was thinking about doing the same thing. The only difference is my EMI filter does not have a spot for mains ground. There is just two wires in and two wires out. I also will not be using a variac so my mains ground has no reason to be used (thus making it probably even safer for my houses equipment. Other than that I will connect the NST case, one end of filter, safety gap, strike rail, and secondary base to RF ground. How does that sound?

From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: Very Confused On Grounding
Date: Sun, 15 May 2005 11:09:51 -0600

Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Terry,

I still think it is best to connect the NST case, your filter, safety gap, strike rail, and secondary base to RF ground. The variac case and EMI filter should be connected to mains safety ground. RF on the NST case will be common mode on the line input and the EMI filter should have a common mode choke (or two) in it. Personally, I dont want to take any chance of a discharge resulting in transient current traveling down (or up) the mains safety ground. This could be catastrophic to any electronics plugged into the mains, whether turned on or off. Grounding the coil system to mains safety ground, I believe, should only be considered when the coil is operated inside where earth ground is not easily available. For this case, the coil should be used with a counterpoise, the power kept low, and great care be taken as to what the streamers can strike.

Gerry

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

At 04:02 PM 5/13/2005, you wrote:
In the Terry Filter he shows one side be grounded to RF (spark gap side) and the other side of the filter be tied to the NST case. Wouldn't this cause major RF on the NST case and maybe inducing into house lines?

Interesting thought... I was thinking the NST case might be hit by streamers in which case it would be best to have it tied to the RF ground. "Maybe" there are situations where the case would be best tied to the AC. But I normally just use the AC ground for safety since it is terrible and conducting RF.

All my coils have MOVs and dual-stage line filters on the AC line too :-) So maybe if you are worried, you would want to do that as well. That stuff can be far back at say the AC power outlet. Mine are inside the variac controller.

Cheers,

        Terry