It's the amps that kill you

[vintner@genie.com]

It's actually the milliamps that kill you.

Here is some interesting information that Craig Toepfer presented at the
EVA/DC meeting in Baltimore in November:

   Human Body Impedance Model
   ==========================

                |
        ________|_________
       |                  |
       |                  |
    ___|___               <
    _______                >       Skin
       |                  <
       |                  |
       |__________________|
                 |
                 <
                  >             Internal Body
                 <                500 ohms
        __________|________
       |                   |
       |                   |
    ___|___                <
    _______                 >      Skin
       |                   <
       |                   |
       |___________________|
                  |
                  |

If the skin is wet or cut, the only impedance left is through the body.
Then it doesn't take a lot of voltage to result in dangerous current through
the body.

                    Physiological Effects of Electric Current
               ==================================================

               Physiological Effect               Hazard Type

               Perception                            None
               Startle Reaction                      Indirect
               Muscle Tetanization (Let go)          Direct
               Ventricular Fibrilation               Direct
               Electrical Burns                      Direct

                    Physiological Effects by Frequency
   ====================================================================

                                      General Current Values (mA RMS)
    Physiological Effect              DC        Line Freq     High Freq

    Perception                        2.0          0.5        0.5 x ff
    Startle Reaction                 >2.0       0.5-7.0    (0.5-7.0) x ff
    Muscle Tetanization (Let go)      30           7.0        7.0 x ff
    Ventricular Fibrilation           56           20         20  x ff
    Electrical Burns                  70           70         70

    Note: ff = frequency factor

    The worst frequency for AC is 50 to 60 hertz.
    Note that AC is generally worse than DC.

 ***********************************************================***
 |  Don McGrath                                         \\        |
 |  Villa Helena Winery   <donmcgrath@alum.mit.edu>   O O O O     |
 |  St. Helena, CA, USA   <vintner@pobox.com>          O O O      |
 |  Tel (707)963-4334                                   O O       |
 |  FAX (707)963-4748    "The Grapes of McGrath"         O        |
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