Re: Safety FAQ (Electrical Hazards)PLEASE READ!
>>From Esondrmn-at-aol-dot-comFri Jul 12 21:56:50 1996
>Date: Fri, 12 Jul 1996 14:00:40 -0400
>Subject: Re: Safety FAQ (Electrical Hazards)
>In a message dated 96-07-11 00:48:22 EDT, you write:
> Hmmm, I've often held a copper rod in the output sparks of a 4" coil. It
>was only 1 kVa so I assume it was quite safe. On a larger coil, say 5 -
> 10 kVa, would it still be safe to do this?
> I know Bill Wysock (spelling?) is renound for sitting atop a 1MV coil.
> The reason I ask, is because when I show my new coil, I would like to be
> able to demonstrate this effect. The coil is running at about 2 kVa.
> Is this safe? (provided I am well insulated and in good tune)
>I have attracted the sparks from my coil running at 2 or 3 kva using a metal
>rod. There is enough current there to make my arm jump. It is definitely
>best to stand on plastic milk crates or some other insulator. You can
>definitely feel it when the sparks jump through your tennis shoes to the
>cement floor. No harm done though.
Ed, Greg, All, PLEASE READ THIS!
Ed, I think you are literally playing Russian Roulette when you stick a
hand held metal rod into the output streamer of your coil running at
3kvA, while standing on a concrete floor!!!!!!!!!!!!!!!
When you start running these kind of power levels (or even less) some
coils have a tendancy to form a corona or even send a streamer down to
their own primaries every once in a while. A grounded strike ring is
often added around the primary to try to prevent this self striking
streamer from hitting the primary coil and thus introducing a high
voltage pulse into the 'bottom end electrics' where it could do
damage to components. These strike rails are not 100% effective.
The streamer can still, and sometimes does strike a point downstairs that
is part of the LETHAL 60 Hz circuitry. When such a contact is made,
any person also connected to a corona/streamer link to the secondary at the
same time will, via the ionized air path, become connected to lethal
60 Hz mains current. You could try the trick you described standing on the
cement floor in your tennis shoes half a dozen times and live, or be killed the
very next time you try it. The fact that the bottom of your
secondary is tied to ground will not save you.
If you isolate your own body well away from the floor and any other
potentially conductive objects in the vicinity, such as sitting or
standing on an elevated insulated platform (I would NOT consider a
plastic milk crate adequate!), then you will survive if 60 Hz is
introduced into the streamer you are in contact with by the mechanism
described above. However, in setting up this insulated platform you
must consider the path that may be taken from streamers that will
re-emerge from your body and head off looking for other targets.
In a safety warning I have about the potential hazards of Tesla coils
mention is made of a stage lecturer while demonstrating how he could cause
long sparks to come out of his fingers (by standing on a specially
constructed coil), was electrocuted when the discharge created an
ionized path to grounded overhead pipes supporting stage back drops,
and the lower voltage but far more deadly 60 cycle current passed
through his body along that path. The name of this lecturer was not
mentioned but I wonder if it is this deceased Transtrom fellow mentioned in
Richard Hull's recent post.
I was dinking around once with a vacuum tube coil drawing 15 inch
streamers to a hand-held, 10 megohm metal film porcelain resistor
about a foot long while standing on a carpeted, elevated wooden floor
in composition rubber soled dry shoes. I inadvertently got the
resistor too close to the primary tank coil (the top end directly
connected to the 3 kilovolt output of the plate supply transformer)
and the high voltage RF closed a path to the primary. I felt an
uncomfortable 60 Hz shock through my entire body. Had that resistor
been a solid metal rod I would have experienced a very painful jolt
or worse, and had I been standing on a cement floor, I'd probably be 'worm
I think the danger of electrocution is just as real by making contact with a
hand held florescent lamp tube, as any solid conducting metal object.
I cringe when I hear of some body contact stunts proposed by people
on this list! The potential (no pun intended) for death is very
real. Be careful!
Happy (and safe) Coiling!, rwstephens