[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] Tesla Coil Output Hazards, Skin Effect?
Ed Phillips wrote:
Ed --- can you give us a brief summary especially of the let-go / no
let-go points?
I was hit with a 15/30 back in 1962 and never forgot it. Hurt like H but
I only touched the wire with the back of my hand. Had I enclosed the
wire with my fist things might have turned out differently.
Dr. Resonance"
Ed asked the question. "dwp" apparently read the paper.
Ed
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla
A web accessible concise summary can be found on pages 4-11 of "A Guide
to Electrical Safety" from the North Carolina Dept of Labor:
http://www.nclabor.com/osha/etta/indguide/ig18.pdf
An interesting graph (Figure 2 on page 4) shows the electrocution
threshold (in mA flowing through the chest) for a typical adult versus
time flowing through the body. The thresholds for a child may be
significantly lower.
The following was extracted from the above paper:
"Based on the research of Professor Dalziel of the University of
California, Berkeley, the effect of 60 Hz (cycles per second) of
alternating current on the human body is generally accepted to be as
follows:
• 1 milliamp (mA) or less—no sensation—not felt
• 3 mA or more painful shock
• 5 mA or more—local muscle contractions—50 percent cannot let go
• 30 mA or more—breathing difficult—can cause unconsciousness
• 50–100 mA—possible heart ventricular fibrillation
• 100–200 mA—certain heart ventricular fibrillation
• 200 mA or more—severe burns and muscular contractions—heart more apt
to stop than fibrillate
• Over a few amps—irreversible body damage"
"Thus, we can see that there are different types of injuries that
electricity can cause. At the 20 to 30 mA range a form of anoxia
(suffocation) can result. This could happen in a swimming pool where
there is a ground loop present (the drain at the bottom of the pool) if
a faulty light fixture or appliance is dropped into the water. Current
would flow from the light fixture to the drain, using the water as the
conducting medium. Any person swimming through the electrical field
created by the fault current, would be bathed in potential difference
and the internal current flow in the body could paralyze the breathing
mechanism. This is why it is very important to keep all portable
electrical appliances away from sinks, tubs and pools."
"Ventricular fibrillation generally can occur in the range of 50 to 200
mA. Ventricular fibrillation is the repeated, rapid, uncoordinated
contractions of the ventricles of the heart resulting in the loss of
synchronization between the heartbeat and the pulse beat. Once
ventricular fibrillation occurs, death can ensue in a few minutes.
Properly applied CPR (cardiopulmonary resuscitation) techniques can save
the victim until emergency rescue personnel with a defibrillator arrive
at the scene. Workers in the construction trades and others working with
electrical power tools should receive CPR training."
Above a few amperes, irreversible body damage can occur. This condition
is more likely to occur at voltages above 600 volts AC. For example, if
a person contacted 10,000 volts, I = 10,000/1,000 = 10 amps. This amount
of current would create a great amount of body heat. Since the body
consists of over 60 percent water, the water would turn to steam at a
ratio of approximately 1 to 1,500. This would cause severe burns or
exploding of body parts. These are the types of injuries that you would
normally associate with electric power company workers. They can also
occur, however, when people accidentally let a television or radio
antenna contact an uninsulated power line. Accidents involving mobile
vertical scaffolding or cranes booming up into power lines can cause
these types of injuries or fatalities."
The above paper implies that, although 30 mA NST may not provide a fatal
shock to a healthy adult, it could cause suffocation and loss of
consciousness. A sustained shock from a 60 mA NST might be fatal (from
ventricular fibrillation) if the victim couldn't free himself from being
part of the current path. Either shock would be quite painful... =<:^o
Bert
--
***************************************************
We specialize in UNIQUE items! Coins shrunk by huge
magnetic fields, Lichtenberg Figures (our "Captured
Lightning") and out of print technical Books. Visit
Stoneridge Engineering at http://www.teslamania.com
***************************************************
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla