RE: Require information re use of working coil in a theatre environment

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Original poster: "Vanderputten, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gvp-at-pvaintl-dot-com>

Werner,

Last year my theatre group put up a production of Frankenstein, complete
with 500 kv of gadgetry created by myself. It actually re-connected me with
a hobby thirty-five years in the past. Anyway, I built several large Jacobs
ladders, but the star of the show was a 1000 watt coil which threw 15 inch
sparks to various devices. It was wonderfully noisy and made the creation
scenes,  

However, as the production  was in an urban setting (Brooklyn, NY),
significant protection was put in place to protect the electronic dimming
system, the mains, the cast and crew, and the audience. As this set was
encrusted with operational electrical components, much care was taken to
fully protect everyone from the mains.

1. The Tesla coil itself was a 3.5" x 15" secondary with 1/4"  flat coil
primary; .0066 uf x 30kv MMC; RQ gap and fan, and a fully protected 12/60
NST, and controlled  driven by a 10 amp variac - full power at 140 was used
twice during the show. 
2. First of all, a Faraday wall was built immediately behind the set wall
and was attached via braded cable to 4" cast iron storm drain (tapped and
treaded). This also was the RF ground for the base of the coil and where all
arcs were directed. This alone greatly reduced RF/EMI noise.
3. The NST was protected with a circuit and components prescribed by Terry
Fritz and Gary Lau. I also had chokes but did not use them, everything else
was there. 
4. Each NST for the ladders had and EMI filter-it was interesting how noisy
these devices were without the filters.
5. During the tech rehearsal the coil fried the dimmer control board which
was mounted in front row (within 15 feet of the coil) of the audience to
facilitate focusing. We remounted it back in the tech-booth (40 feet away)
and used chicken wire attached to another  RF ground. Also, the board and
all other 'sensitive' components were plugged into a box with an EMI filter.
6. All electric devices on the set (several NSTs, a large noisy motor and
compressor) were isolated on the mains distribution panel; the coil and the
ladders each had their own circuits at the panel. (total consumption was
about  40 amps and 115v.) 
7. The mains are the most dangerous aspect of such productions. For total
realism in timing queues, all high voltage devices (anything on the set
requiring mains voltage) were operated by the cast from practical knife
switches(antiques ala ebay) mounted on the set and which were part of a low
voltage(24v), low wattage, control circuit which drove a series of relays
back stage (also protected). This allowed for the best possible execution of
practical devices by the cast while fully protecting them from shock. There
were redundant switches back stage and in the tech booth to run or kill each
device if there were problems - there were none.
8. The cast and crew were well trained on the devices and blocking was
rigorously defined to keep them away from the coil at key times. Despite the
relative harmlessness of these devices, the cast was pretty terrified of
them, which was good!
9. The Tesla  coil was operated independently from the tech booth but the
technical director (myself) who had designed and built the set. This insured
that blocking errors were 'managed'.
10. CO2 based fire extinguishers were mounted on the set to afford extra
fire protection.
11. Some observations- 
a. No one every received as shock; there were no incidents
b. My digital camera was unaffected by the coil, even at five feet.
c. The sound systems were unaffected (tape, mini disk, and cd).
d. People with pacemakers were unaffected at 15 feet - you should search
these threads for more on this topic. We had no issues with the gray hairs
e. Hearing aids were unaffected 
12.  We didn't have an insurance issue. However, I would emphasize two
concerns:
a. I would think that if you have qualified and licensed electricians doing
the connections according to a rigid and 'to code' spec, a low voltage
control system, and a 'degreed' geek designing the RF protection, it should
be insurable.
b. There must be someone highly qualified and totally familiar with all such
equipment who must be there for every performance, This, I think, is the
biggest impediment to brining up such productions. While my participation
was for only several minutes, I enjoyed the show each night. 

Hope this has been helpful.

I can also be reached at garyvp-at-eathlink-dot-net or gvp-at-pvaintl-dot-com if you need
additional help.

Gary



 -----Original Message-----
From: 	Tesla list [mailto:tesla-at-pupman-dot-com] 
Sent:	Tuesday, September 24, 2002 2:23 PM
To:	tesla-at-pupman-dot-com
Subject:	Require information re use of working coil in a theatre
environment

Original poster: "Flaming Eye by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<flamingeye-at-optusnet-dot-com.au>

Hi all
 
Question - has anyone used a working Tesla Coil in a production, if so could
you post information.

I am the production director of an opera company in Australia and we are
working on a production exploring the life of Nikola Tesla.  I am interested
in contacting anyone who has used one in a public performance environment as
there are serious safety issues which in turn attract the dreaded insurance
company vulture leeches.
I am aware of most of the safety hazards and am primarily interested in
discussing these issues with those who have been involved in a production
where
public attended and the theatre company managed to obtain public liability
insurance.

Regards
;-)

Werner Ihlenfeld