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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.