Re: You use a utility transformer?!

To: tesla-at-pupman-dot-com
Subject: Re: You use a utility transformer?!
From: Terry Fritz <terryf-at-verinet-dot-com>
Date: Tue, 08 Sep 1998 20:49:33 -0600
Approved: terryf-at-verinet-dot-com
In-Reply-To: <35F5CA11.6D04-at-pacbell-dot-net>
References: <3.0.6.32.19980908064844.0090a400-at-verinet-dot-com>

Hi Ed,

	I used to work for the power company.  Although I was a 375 kV, 600 amp
guy, the "low" power 14400 volt lines are by far the most dangerous.  The
super power lines are so dangerous that everyone is extremely careful and
they are hard to get hold off.  However, the 14400 lines are strung all
over the place and all kinds of people can get tangled up in them (phone
installers, cable TV, kid's kites, etc.).  So more people are killed by
these lines than any other.  An amazing number of people live through
contact with the super voltage lines because they are blasted clear
(although their injuries are horrific!!  You are better off dead in most
cases).  14400 will not throw you clear, it will simply fry you.  You can't
let go and it can arc through air to get you.

	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




At 05:21 PM 9/8/98 -0700, you wrote:
>It's not obvious to me that a distribution transformer would
>necessarily be more lethal than a neon sign transformer with equivalent
>voltage output.  Any current over a few mils, (passing through the
>chest) should be lethal in the long run .  I know there's a lot of data
>on morbidity vs time of exposure, but I think getting across a 15 kV 60
>ma NST (say between the hands) would have the same results as getting
>across a 15 kV, 100 kVA transformer.
>
>Ed
>
>

References:

Re: You use a utility transformer?!

From: Cabbott Sanders <cabbott-at-cyberis-dot-net> (by way of Terry Fritz <terryf-at-verinet-dot-com>)