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Re: You use a utility transformer?!
" So why are neon's relatively safe and pole transformers more
dangerous?
It is because of the current limiting. Assuming the body will have a
resistance of 1000 ohms (that varies much), a 60 mA neon will deliver
about
3.6 watts of power to the victim (that load will drop the voltage to 60
volts). Now take away the current limiting and deliver say 14.4 amps at
14400 volts. That comes out to a toasty 200 kilowatts. Or 58000 times
the
power! If a man were 150 lbs. of water (and my math is right) that much
power will bring a person to a boil in about 25 seconds!!
Another "fun" way of looking at it is to draw and arc with a
neon and
imagine throwing yourself into 58000 of them!
Roughly, 100 ma and above is considered lethal so neon
transformers are
designed to limit under that level to be somewhat safe. Of course, if
you
are unlucky and get a good hold, you can get killed by a neon.
Make no mistake, coilers that use pole transformers are in an entirely
different league when it comes to safety. They can only make one
mistake,
their last!
Hope this explains it. Yuck! What a nasty subject! :-(~
Terry Fritz"
Terry:
I agree that an NST won't cook you, and that a distribution transfomer
surely could. However, seems to me that I have read (in connection with
the introduction of ground fault indicators in house systems) of studies
indicating that currents much less than 100 ma can cause ventricular
fibrillation and resulting death if not treated immediately. In my
Lindsay books' "Neon Signs" by Fink (circa 1935) the statement is made
that NST's don't put out enough current to kill, and that the main
danger in getting across one would be that of falling off the sign. I
sure don't want to test that theory. Is there someone on the list who
has enough knowledge on the subject to enlighten us? Should be a
subject of considerable interest.
On a related topic, due to trouble with varmints (skunks and possums)
digging up a newly installed back lawn, I have installed an "electric
fence" around our back yard. Originally it was excited with a high
voltage source consisting of an auto ignition coil fed with a transistor
interruptor and pulsing a couple of times a second. Current in the coil
was such that the thing would generate a 1/4" spark across the
terminals. This discouraged the miserable critters for almost a year,
but then they began to ignore it. I escalated the power into the coil
until it would throw half-inch sparks at a pretty good rate and that
worked for a little while only, with lawn damage returning with a
vengance (sp?). My wife kept bugging me to "do something about "IT"
NOW!!!!!!!!!!!!". In order to silence here I hooked up a 9 kV, 60 ma
NST with one side shorted due to carelessness (opening up the gap too
far like a beginner) while playing with a small TC. Case is tied to
ground and the remaining hot side to the fence, which consists of two
strands of wire, one about 4" above the ground and the other at 8".
There was no further lawn damage for a couple of months, but no other
indications of encounters with the wires. About a week and a half ago I
found a thoroughly cooked skunk across (actually under) the wires.
After I went to work my wife discovered a small possum also across the
wires. The humane society came and hauled the remains away without
comment. That evening I was repairing the broken wires and discovered
two big rats which had also been zapped.. Four hits in one night, three
apparently after the first animal had gotten it. Since then the score
is three more skunks, one of which burned up right outside our kitchen
window and created a most distressing smell in the house.
Point of all this is that NST's CAN be lethal, at least under some
circumstances, and should be treated with as much respect as their
bigger brothers.
Ed