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Re: [TCML] A Safe Tesla Coil - was: Tesladownunder update, briefcase coil, lots of sparks etc



Safety is complex. Note that a 4kV 20mA NST does not put out 80W. Probably half that as it is open circuit voltage and closed circuit current. My coil is very inefficient and I would be surprised if it put out 5W. Measuring this could be done by calorimetry with a water resistor I guess. Sure 3 inch sparks from this coil are enough to cause muscular contraction, but are highly unlikely to have sufficient current to give cardiac effects - and I have significant experience putting electric current through the heart with pacing or cardioversion.

Cheers
Peter www.tesladownunder.com





----- Original Message ----- From: "Dex Dexter" <dexterlabs@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, June 26, 2009 11:16 PM
Subject: Re: [TCML] A Safe Tesla Coil - was: Tesladownunder update,briefcase coil, lots of sparks etc




I am also curious to know how exactly Transtrom got killed!?
I recall reading paper somewhere that it was solely due to the connection of a 5 ft arc from his arm to the grouded stage framework.
Not mention of any arcing to the primary coil!
If true that means only one thing:big tesla coil arcs have potential to electrocute.
I really believe that.
3" spark from my body as TC top load to a grouded pipe caused jolts in my hand.
Input power level below 50 W!
So,what is a safe Tesla coil power level?
Safe electrical power level in general?
50 V (50/60 Hz) and 50 mA are prooven to be life threatening values.
That's P=50V * 0.05A = 2.5 watts only.
Of course,tesla coils are less dangerous but good to know how low power,if everything goes wrong,is enough anyway.

Dex










Firstly, mains earth is the RF earth and goes to all the metal in the
briefcase which is the centrepoise. Secondly, spark length is such
that it is just not going to connect through the PVC pipe surround
separating the primary and secondary. The primary is fully enclosed.
Child use means the child holding a small neon tube that is earthed
and drawing sparks. It is hard to imagine a circuit path that will be
a problem in this situation.
I have always been a little skeptical about the situation you describe
anyway. Simultaneous sparks from primary to seconday plus toroid to
subject seem a bit far fetched. The circuit path for a mains = RF
earth would be very largely in favour of flow through the base of the
secondary rather than through the subject.
Do you (or anyone) have reasonable evidence that this has increased
secondary current and if so why aren't we exploiting this all the time
to increase our TC sparks?  I am aware the Henry Transtrom was said to
have been killed in this way but I would have thought it was just a
high power coil that was the problem.

Cheers
Peter
www.tesladownunder.com


----- Original Message ----- From: "Derek"
<tesla@xxxxxxxxxxxxxxxxxxxxxxxx>


Peter,
..... I am interested as to how you have made this coil safe "for
supervised children to use". I realise that the power levels and
performance mean that the risk of electrocution directly are very
small, but to my mind the most dangerous aspect of you coil is the
possibility of a primary to secondary arc whilst a "tasting" was in
progress. In this case there is a very real danger of connecting the
6Kv@30mA output from the NST via the secondary and arc channel to the
"taster".

Have you designed the coil in a way to limit or prevent this
possibility ?

   Derek

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