Even for smaller coils (i.e. a single 15kv/30ma NST), should I consider
tying NST to a new/RF ground (8 ft ground rod) if I want to avoid any
transients into my neighbor circuits? I live in an old duplex house with
horribly out of date wiring.
I do have a Terry filter and line filter, but I need to be extra specially
careful. I assume that RF ground is also secondary ground correct (thus RF).
Any other steps I can take? Note that this is a traditional static gap coil.
Thanks!
Matt
On Tue, Jun 19, 2018, 9:52 AM Chris Boden <cboden@xxxxxxxxxxxxxxxx> wrote:
> This depends on usage. If it's a little JL or you're just screwing around
> with an NST, mains ground is what you want. If it's part of a larger TC
> system then RF ground is better.
>
> But regardless of application, Ground it.
>
> On Mon, Jun 18, 2018 at 9:40 PM, Gary Lau <glau1024@xxxxxxxxx> wrote:
>
> > I disagree with the advice:
> > > 3. GROUND THE CASE OF THE NST
> >
> > The case of the NST is tied to RF ground and is full of high voltage RF
> > transients that you do not want feeding into your mains.. Unless the
> coil
> > is relatively low power and there is no alternate ground or counterpoise
> > available, you should not be connecting RF ground to mains ground. I
> can't
> > think of any fault condition or inadvertent touch where having the NST
> case
> > tied to mains ground offers any safety advantage.
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > On Sun, Jun 17, 2018 at 6:44 PM, Chris Boden <cboden@xxxxxxxxxxxxxxxx>
> > wrote:
> >
> > > Greetings Mr.Janota :)
> > >
> > > NST's are current limited and operate typically at a maximum of 15kV
> > (with
> > > 12kV and lower being quite common as well).
> > > The typical max current output will be 60mA.
> > >
> > > What this means is it Most Likely, Probably.....Unusually....wont' kill
> > > you
> > > if you brush against the output, are a rigorously healthy adult, dry,
> and
> > > nontrivially lucky.
> > >
> > > This is as opposed to things like Pole Pigs at 10kVA or more (we have
> > > 100kVA pigs in the lab) with no current limiting which are reasonably
> > > considered to be fatal (it's not instant, and it hurts the whole time).
> > > There are also pulse capacitors (typical in our lab is 20kV to 50kV
> with
> > > 10kJ energies) those don't just kill you, they blow parts off. We have
> > > 400lb caps here that are in the "clean you off the ceiling with a
> sponge"
> > > levels of deadly.
> > >
> > > That's a long way from your NST, but the idea across the spectrum is
> the
> > > same. These toys are not for the emotional, impulsive, or stupid. They
> > will
> > > hurt you the moment you don't respect them, and kill you if you're
> > > reckless.
> > >
> > > That's the point.
> > >
> > > There are millions of people who would like to own a powerful Tesla
> Coil.
> > > But very, very few get that far. The fundamental price to own a coil is
> > > simple, be smart enough to build one. It's not hard, but you have to do
> > it
> > > yourself. Along that path you will have to learn hundreds of new
> things,
> > > foremost is safety and a healthy respect for HV. Consider how few
> people
> > > you know who have ever run a marathon. The rough number is often quoted
> > as
> > > 1% of 1% of the people in America have ever run a marathon. The number
> of
> > > people in the history of the world who have ever successfully built a
> > > working Tesla Coil wouldn't fill a single run of the Chicago marathon.
> > This
> > > is a very small community.
> > >
> > > To the average person Electricity is composed mainly of magic. It's
> > > dangerous and terrifying. In reality, it's just science. The mechanisms
> > of
> > > electrical power have been pretty well worked out by people far smarter
> > > than me. We can build chips at the nano-scale with billions of wires
> > only a
> > > few atoms wide carrying energies less than a mouse's fart, and we can
> > > wrangle million-volt power lines across the desert. But to the average
> > > person they understand as little about how the power gets in their
> > computer
> > > as they do about what actually happens when they flush the toilet.
> > >
> > > You should have a respectful, healthy fear of HV, but not a crippling
> > one.
> > > It's not magic, and it won't jump across the room and bite you. Some
> > simple
> > > things to remember will help you a lot.
> > >
> > > 1. Keep the plug in your pocket when you're working on the NST. If the
> > plug
> > > isn't in your pocket, then don't touch it.
> > > 2. 15kV with a beginner wants a safe radius of 2 inches to anything,
> and
> > 3
> > > feet to anything that's alive. Keep the HV conductors 2 inches from the
> > > case and you're not going to have any problems.
> > > 3. GROUND THE CASE OF THE NST. The bottom-center hole on a US outlet
> (the
> > > mouth of the face) is Ground. This should connect to the uninsulated
> lug
> > on
> > > the side of the NST. The NST will have two big insulated lugs (the HV
> > > terminals) two smaller insulated lugs right next to each other (the LV
> > > terminals), and one uninsulated lug that just looks like a bolt
> sticking
> > > out the side....that one is the ground.
> > >
> > > And lastly, while most of the people here would never admit it (and
> > > certainly never publicly), the vast majority of us have been bit at
> some
> > > point because we did something stupid and got a hard lesson in pain.
> I've
> > > been bit a few times and thankfully, by sheer dumb luck I survived
> them,
> > >
> > > so far.
> > >
> > > Good luck :)
> > >
> > >
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>
>
> --
>
> Chris Boden
> President
> The Geek Group National Science Institute
> www.thegeekgroup.org
>
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