RE: Safe parameters for stupid human Tesla coil stunts

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Owen Lawrence" <owen@xxxxxxxxxxxx>

Thanks to everyone who posted a response.  I read that thread from the
July/2001 archives from front to back, too.  When I built my first Tesla
coil, it was a small one, with an ignition coil for the primary.  Part of my
demonstration at the science fair was to show that you could feel the shock
when you touched the primary coil, but not the secondary.  If I remember
correctly, the coil resonated at 32MHz, and everything I had read up to that
point said the skin effect was what made it safe.  And I had read everything
available to any 15 year old on the subject, up to that point.  Glad nothing
bad happened.  (And 1st prize was mine, too. :) )

Now I've got a 30mA neon sign transformer, and a second waiting to be added
when I get more experience.  That's probably about as far as I want to go
with it.  I have never taken a shock off any of this stuff, and have no
intention of doing so, especially now after reading your point #2, below.  I
don't want to be afraid of my toys, but I am careful, one hand in the
pocket, etc.  I guess I want to hear that if an arc does happen to reach me
(HV can be weird stuff sometimes) I'm not going to die from it.  (I know, I
know, you can't say 100% for sure I'm not going to die from it, but say what
you can.)

People perform these stunts so they can be seen.  When I find a cool video I
show it to my colleagues at work.  They ask questions, and I give the best
answers I can.  Until now I've never said, "Hey, check out this really
really dangerous thing this person is doing!"

  - Owen -

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, December 22, 2004 7:17 PM
To: tesla@xxxxxxxxxx
Subject: Re: Safe parameters for stupid human Tesla coil stunts


Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 12:21 PM 12/22/2004, you wrote:
>Original poster: "Owen Lawrence" <owen@xxxxxxxxxxxx>
>
> >       I see these pictures of people with thimbles on all fingers,
> > radiating sparks.  What would you consider to be safe parameters for
> > performing stunts like this?  Minimum secondary frequency, maximum
primary
> > transformer current/voltage, stuff like that.  Thanks.
> >
> >   - Owen -

Hmmm... "safe" is somewhat of a subjective term.

1) Big risk: typical tesla coils work at frequencies where your nerves
don't respond to the shocks, so you don't feel the damage as it
occurs.  You'll feel it later with the RF burn

2) Big risk: Skin effect is bogus, as far as tesla coil frequencies go. The
"skin depth" is on the order of feet.  Nope, that RF power is going right
through your body.

3) Big risk: Startle effects can cause you to fall off and spear yourself
on some component (or break your leg, etc.), touch something you shouldn't,
etc.

4) Big risk: using a conductive suit/thimbles/ground wires can mitigate
"some" of the risks, but without a lot of experience, it's hard to know
just how well it's mitigated.

The risks don't come from exceeding some predetermined set of specs
(frequency, voltage, etc.), but from a lack of thorough understanding of
what's going on and what to expect.

Let's compare to rock climbing.  You can fall from 4 feet and be seriously
injured or killed.  You can climb thousands of feet and not be hurt.  What
makes rock climbing safe (or not) is a matter of understanding what's going
on (training and experience), use of the right equipment, and some good
luck.  You've got to have both the understanding AND the
equipment.  Likewise with a tesla coil. You've got to have the equipment
(chain mail suits, thimbles, etc.) and the understanding to know when it's
safe(r).

So.. to return to your original questions:

A tiny tesla coil can kill or injure (in surprising ways!). It's not the
size or operating characteristics of the coil that make it safe, but how
the stunt is done.  And, like all stunts, there's an element of probability
in it.  The real safety is in the backup measures (or a careful
consideration of what will happen, and mitigation) when something doesn't
work quite right.

Compare to seat belts in cars.  Wearing a seat belt doesn't directly affect
the task of driving the car (or riding in it). People drive every day
without their seat belt on. Is it unsafe? Sure. But accidents are
relatively rare, so you can do it for a long time without you personally
being hurt.  You can't really evaluate the efficacy of seat belt wearing
based on personal experience, until you've been in a situation where the
seat belt did some good (or not).

Risk and safety is also a very, very subjective evaluation.  People will
voluntarily assume remarkable risks, for some perceived benefit that makes
it "worthwhile".  This analysis cannot really be approached from a
"risk/benefit analysis" standpoint.  Say you ride horses and jump fences.
(or, jump out of airplanes at high altitudes) This is a fundamentally
dangerous activity.  However, you might derive sufficient satisfaction from
doing it that you decide it's "safe enough", especially if you are single
and don't have anybody depending on you.  In fact, the excitement and
prospect of "cheating death" makes it more attractive.  However, a person
who is married with small children might evaluate that risk in an entirely
different way (even though they may actually be a better/safer rider or
parachutist, by virtue of increased experience).

A professional stunt performer (i.e. Ms. Stampe) makes those tradeoffs
every day.  They willingly assume some amount of additional hazard in
exchange for fame and fortune (although precious little of each, when it
comes right down to it..).  A lot of stunt performers also do it for the
thrill and not so much for the money and reputation: I'd say that is
particularly true among the early-20's group.  There are a lot of
inherently dangerous professions (chemical/oil industry worker is one,
racehorse jockey is another), but in all cases, it's a PROFESSION...
there's an implication that you want to continue doing it for a while, that
there's some rationality in how the job is done, and that there's some
aspect of training and knowlege that goes into it.  The professional
expects to do it and survive to do it again.

This is why you hear that professionals despise the amateur.  Why?  Because
an incredibly foolish or stupid amateur can always be found to do something
incredibly dangerous.  The amateur is going to do it once or twice, and
even hideously dangerous things might have a reasonably low probability of
"going wrong".  If the odds of dying are 5%, the amateur can probably get
away with doing it a few times without dying.  To paraphrase P.T.Barnum, if
you're a producer, and you've got something the pros won't touch, you can
probably find an amateur who will do it for free.