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LED test lamp. (Risk of death)

Discussion in 'Lighting' started by Clive Mitchell, Jan 25, 2006.

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  1. Don't try this at home kiddies.... You WILL die. :)

    The things you do during your lunch break at work.....

    The picture below shows me with a 1 metre section of red LED tubelight
    clenched between my teeth. So what's so special about that? The LEDs
    are being lit entirely by 240V mains current flowing up my right arm,
    across my chest, down my left arm, through the LED circuit in the tube
    and to earth.

    Just for safety (!) a resistor has been added to limit the current to
    non heart fibrillating levels. Yeah, it's both stupid and hideously
    dangerous, but hey that's your Uncle Clive for ya. ;)

    It's a nice demonstration of how much more efficient the LED stuff is
    than the old lamp based stuff. The current is being limited at somewhat
    less than is required for full LED brightness, but that was mainly due
    to the availability of the safety resistor value and my courage at that
    point. It was still enough to clamp my grubby mitts firmly onto the
    connections and hurt like hell.

    I repeat.... DO NOT TRY THIS YOURSELF!!!!!!!! This stunt was
    pulled with calculated current flow and limiting within known safe
    handling levels for my larger than average frame. The same current
    could cause death in a smaller person.

    http://www.emanator.demon.co.uk/testlamp.jpg
     
  2. What did you calculate to be a safe current of power-line-frequency AC
    flowing arm-to-arm through your chest cavity? Or someone elses?

    Many web references support 100 milliamps to be the low edge of the
    "danger zone", and a lesser number say/support 50 millimaps for that.
    However, it really appears to me that the danger is merely lessened at
    99 or 49 milliamps, and merely lessened more at 24 milliamps, as opposed
    to being reduced to zero or even to a risk low enough for me to want to
    bet my life on.

    Oh yes, most high-efficiency-red LEDs glow plenty bright at 10
    milliamps or less. (How much curent do you estimate was flwoing through
    your chest cavity?) The survival rate for a 10 milliamp
    power-line-frequency arm-to-arm shock is probably very high, but would you
    want to bet your life on it?

    I certainly see lack of reliability in electrocution! There is a
    widely-published range of currents most likely to cause ventricular
    fibrillation - the most common and most-achievable electrocution
    mechanism, and most sources say 100 mA to 1 amp for that. Above that the
    chance of dying lessens but you also have not only the (lesser but not
    zero) risk of ventricular fibrillation, but also cardiac arrest!
    How about when convicted criminals are sent to "The Electric Chair"?
    Voltage and current there are designed to "fall back" onto brute-force
    sure-kill methods, such as:

    * Paralyzing breathing and/or heart long enough for the brain to be too
    impaired by lack of such for breathing unless resuscitation is performed

    Failing that,

    * Cooking of one or more vital organs
    * Paralyzing breathing and/or heart long enough to cause brain-death

    As unreliable as electrocution is, I would say similarly unreliable is
    lack of electrocution from a "safe" electric shock.

    - Don Klipstein ()
     
  3. WM

    WM Guest



    You, sir, are a wacko! :)
    But I suspect you knew that already.

    And now will there be an X-rated version of this picture where the
    current flows through rather more intimate parts of your anatomy?
     
  4. I hereby nominate Mr. Mitchell for the 2006 Darwin Award.
     
  5. The ever popular Tingle Tron was used as the current limiter, so given
    that the LED circuit would have dropped about 70V I guess the current
    might have been just under 8mA. The Tingle Tron has been used
    successfully on a large range of adult body sizes at the full 8mA
    output. To date it's not managed to kill anyone, even when the current
    is sustained for several minutes.

    The real question is... How far can I go without interfering with my
    heart? There's only one way to find out and given that CPR isn't
    particularly reliable I'm not sure it's a sensible experiment. :)

    I need to start with a new hand held connection. The current design
    causes extreme finger contraction and discomfort.
     
  6. 30mA vertically through the body can cause asphyxiation by contracting
    the diaphragm. 100mA is considered the point of risk for adverse heart
    effects. 1A for fibrillation.
    Phone ringing voltage here about 75V at 25Hz. Very nippy.
     
  7. Oh, no. Darwins can only be awarded once the subject has been removed
    from the gene pool - either by death or by losing the ability to
    procreate. Besides, Clive is only crazy - not stupid. :)
     
  8. The range most likely to cause fibrillation, according to most sources,
    is 100 milliamps to 1 amp. I don't think the risk falls off really
    sharply going a little outside this range - as in I suspect 80-90 mA is
    not much better, as opposed to "somewhat safe" from causing fibrillation.

    Above 1 amp flowing through the chest cavity, the risk of fatal heart
    malfunction decreases, but not to zero, and includes the risk of cardiac
    arrest as well as some risk of fibrillation.

    - Don Klipstein ()
     
  9. scott

    scott Guest

    The ELCB/GFCI on my house and most others in Australia is rated at 30mA at
    240V, so someone in authority considers that to be a reasonable limit.

    What about electricians test pencils? They have a neon in series with a
    resistor, and it considered safe to touch that to 240V on one emd and a
    human finger on the other end.

    Regards

    Scott Forbes
     
  10. TKM

    TKM Guest

    What's your power factor, Clive? I"m trying to figure out how many watts
    were disapated on the inside. Did you feel any residual warmth anyplace you
    can talk about? );

    Terry McGowan
     
  11. TKM

    TKM Guest

    Indeed, we do want and need Clive to stick around. Recall that the trip
    current of GFCIs is only 5 mA. Maybe that's conservative and sized for
    children, the elderly and small animals; but if current finds the right
    path, any mA amount can cause damage.

    Terry McGowan
     
  12. David Lee

    David Lee Guest

    Scott wrote...
    Standard UK RCD parameters are 30mA/30ms, although 100mA devices can be
    fitted to consumer units to prevent nuisance tripping of the whole system
    when individual circuits are protected by 30mA devices.

    David
     
  13. TKM

    TKM Guest

    My mistake. There are several standards for GFCIs in NA. Depending upon
    the application, the trip rating can be as much as
    20 or 30 mA -- even for home situations.

    Terry McGowan
     
  14. 30mA in the UK, and I'm not even going to describe the experiment I did
    a while back that passed enough current through my body to trip the
    house RCD.
     
  15. I believe my power factor is unity. I'm certainly not adding capacitors
    to the equation anyway. :)

    As far as warmth goes... 10mA at 240V is just 2.4W, so not much heat
    for a couple of big arms and a broad chest. Localised skin resistance
    could be an issue here though.
     
  16. They generally pass a very low current in the 250uA region, although I
    did have one once that passed a significant 1mA. Pretty unpleasant to
    use if you were earthed well.

    In the company I served my time with, one of the electricians took his
    neon driver apart and dropped the resistor. Since it looks like a
    little slug of metal, that's what he replaced it with. He then
    proceeded to test it on a live connection with very exciting results.
    :)
     
  17. Chris Carlen

    Chris Carlen Guest


    What about muscle stimulation machines such as used in physical therapy?
    I used to beg them to keep increasing the current. I finally got it
    so high that they were simply shocked (pun intended) that they had never
    had a patient so high before. I forget what it was, 40mA or something.

    It would make my back practically numb for a few hours. Totally delightful.

    But I think this is highly diffused current, and not deep penetration.
    Mostly on the surface.

    But I wonder how they know for sure how to design the machines so that
    folks don't get fried. I can't recal if the electrode was all one large
    sheet, of if there were individual ones. I think it gave a quadrature
    type of output.



    --
    Good day!

    ________________________________________
    Christopher R. Carlen
    Principal Laser&Electronics Technologist
    Sandia National Laboratories CA USA

    NOTE, delete texts: "RemoveThis" and
    "BOGUS" from email address to reply.
     
  18. You are wearing your teeth at the time?

    (Ducking and running for cover)
     
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