Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Terry,
Excellent document you found!! Dangers of electrical shock is
everywhere in todays world. This document you shared, well, I plan
to use at work to educate some of the field engineers. I recently
finished getting our products Listed and Registered. Quite an ordeal
and education for any engineer to go through this. I fought long and
hard to make our systems safe (240 VAC, 20A units). 3 years of
putting my foot down payed off! The system passed with flying colors
(Hi-Pot testing, High Currents on Ground, Temperatures, everything).
They did a very detailed measurement and testing. I was quite amazed
at the process. High current AC is something new for my field
engineers (their knowledge is mostly mechanical). This document will
help me educate them.
I understand the SISG concern. Your right. New coilers with little
or no HV experience (or even electrical experience) can easily head
the SISG route. I am a prime example. Although I was a degreed
electronic engineer, I had no high voltage education or experience
when I started coiling. I started with a pole pig (not the smartest
route to take)! Luckily, I educated myself here on the list and
elsewhere. But safety protocols (other than the obvious of not
touching anything) I was still very green.
The SISG situation is very similar with respect to the dangers. The
patent thing is expensive (as you know). I personally wouldn't go
that route unless the product could pay for the patent lawyers.
Disclaimers are very important and a document of safety protocols
specific to the SISG may be wise. Standard NEC safety for the
voltages and currents call out specific safety requirements. It
would be a good idea to start there for the safety "requirements"
and incorporate at least the basics into the design. This includes
safety ground tied to a conductive casing around the electronics,
wire sizes, high voltage/current wire bends and routing, fusing,
etc..). Those are some of the type of items to pay attention to.
Take care,
Bart
Tesla list wrote:
Original poster: Terrell Fritz <terrellfone@xxxxxxxxxxxxxxxxxxxxxxx>
Hi,
I recently pulled the PIRANHA SISG web site temporarily off-line
until I could improve the safety warnings and data. Since
PIRANHA's charging system can be "thrown together" very quickly, I
am very concerned that "anyone" could make a powerful (too
powerful) system without much "HV safety knowledge". With two old
microwave ovens and a screwdriver, I could put it together in about
1/2 hour... The SISG gaps still serve an "entry barrier" for many,
but that could change very quickly as fully assembled boards become common...
In studying its safety and possible risks, I ran across this very
nice safety paper:
http://www.nclabor.com/osha/etta/indguide/ig18.pdf
Page 4 has a simple human body model and a graph that "sort of
determines" what various shock levels will do to a person. Such
data is easy to simulate with a circuit simulator to find peak and
RMS currents that make be delivered to a person in contact with
various parts of a Tesla coil system. The "death vs. time" and
levels that cause "fibrillation" as opposed to "just stopping" the
heart are pretty well explained...
PIRANHA actually delivers far less power than I thought into
various human fault loads (still easily deadly) but the added load
is small on fuses and other conventional safety devices. The
output arcs still stop, but the circuit "happily" fries the person instead...
So I was wondering if the human model in Figure 1 has a more
accurate version for voltages in the 5,000 to 25,000 volt
range? Also, if there is a larger graph like than in Figure 2 that
would extend into the 20 amp range? The graph could be
extrapolated for 2 orders of magnitude, but that might not be very good.
Hopefully, I can fairly well "predict" the effect of touching
various parts of the system in an effort to convince people that
they really need to be "super safe" and fully enclose and insulate
the thing like "I did" in my design. I also must ponder the known deaths:
http://hot-streamer.com/TeslaCoils/Misc/Deaths.txt
and what safety measures could be taken "today" to eliminate the
possibility of those specific accidents from recurring.
It would be nice if systems like PIRANHA were not only among the
easiest and most powerful Tesla coils, but also among the "safest"!!
There will be a "temptation" to "skip" the NST and low powered
coils by the "newbee" especially if systems like PIRANHA are
"easier and simpler" to make... I am not sure how to "empress"
upon them the extreme dangers of such high powered state of the art
things... An advanced high powered coil, but the simplest to
make... It could be a very "deadly" combination... Have to figure
out how to "fix that" ;-)
All thoughts, public and private, welcome ;-))) I guess it is time
to push the safety warnings to "another level" now that we are
getting "too good" at this stuff ;-)
Cheers,
Terry
BTW - Interesting reading:
http://www-training.llnl.gov/training/hc/HVResearch/Grounding.html
http://pad39a.com/gene/shock.html
BBTW - I might have to "push" the "PIRANHA" trademark and patent
thing now... In today's world market, that is typically
worthless... But it does provide significant leverage in the case
of the "abuse" of the technology...