Re. how to hook up an EMI line filter - I put up a web page detailing how
to hook it up, how NOT to hook it up, and why. The full answer is more
nuanced than just forwards or backwards - and again it involves grounding.
See http://www.laushaus.com/tesla/emifilter.htm
Now back to grounding. I previously wrote:
> I can't think of any fault condition or inadvertent touch where having
the NST case tied to mains ground offers any safety advantage.
Actually I can.
If one were to "assume" that touching the case of an energized NST was OK,
and
If the NST case were tied to an RF ground or counterpoise that did not have
a low impedance path to mains-ground, and
If some other body part of this person was in contact with a grounded
object, and
If the NST had developed an internal or wiring fault that provided a path
from AC-HOT to the NST case,
... then there is a credible risk of shock. This scenario is far more
plausible where the NST is powering a neon sign and the victim is not a
high voltage enthusiast. Hopefully everyone reading this understands that
touching ANYTHING on an operating Tesla coil is not a good idea.
Unfortunately I cannot think of any way to both eliminate this hazard and
to keep RF ground transients out of your mains.
Gary Lau
MA, USA
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On Tue, Jun 19, 2018 at 8:20 PM, Matthew Sweeney <msweeney23@xxxxxxxxx>
wrote:
> Thanks Dan, I did pickup some of those little line filters, but I have to
> hook it up 'backwards' right?
>
> Matt
>
> On Tue, Jun 19, 2018, 4:06 PM Daniel Kunkel <dankunkel@xxxxxxxxx> wrote:
>
> > Matthew,
> > You might consider using a commercial line filter to keep RF nasties out
> of
> > the supply line. You can get a 10-20amp until for around $10-20.
> > ~Dan
> > Kansas City area
> >
> > On Tue, Jun 19, 2018 at 10:57 AM, Matthew Sweeney <msweeney23@xxxxxxxxx>
> > wrote:
> >
> > > 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 horribly out of date wiring.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 :)
> > > > > >
> > > > > >
> > > > > <http://www.avg.com/email-signature?utm_medium=email&;
> > > > > utm_source=link&utm_campaign=sig-email&utm_content=webmail>
> > > > > Virus-free.
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> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > >
> > > > Chris Boden
> > > > President
> > > > The Geek Group National Science Institute
> > > > www.thegeekgroup.org
> > > >
> > > > --
> > > >
> > > >
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