Possible Explanations Requested

[celtic]

I don't care who you are, now that's funny.

You should have been here over the weekend...all the mods were pulling double-duty closed and deleting posts..it was a riot.


j/k

 

[robbietan]

got this from www.osha.gov

Current Reaction

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Below 1 milliampere Generally not perceptible
1 milliampere
Faint tingle
5 milliamperes Slight shock felt; not painful but disturbing. Average individual can let go. Strong involuntary reactions can lead to other injuries.
6?25 milliamperes (women) Painful shock, loss of muscular control*
9?30 milliamperes (men) The freezing current or " let-go" range.* Individual cannot let go, but can be thrown away from the circuit if extensor muscles are stimulated.
50?150 milliamperes Extreme pain, respiratory arrest, severe muscular contractions. Death is possible.
1,000?4,300 milliamperes Rhythmic pumping action of the heart ceases. Muscular contraction and nerve damage occur; death likely.
10,000 milliamperes Cardiac arrest, severe burns; death probable
* If the extensor muscles are excited by the shock, the person may be thrown away from the power source.

Source: W.B. Kouwenhoven, " Human Safety and Electric Shock," Electrical Safety Practices, Monograph, 112, Instrument Society of America, p. 93. November 1968.

 

[Mike03a3]

I have a few possible explanations myself, all of which are unlikely. So I?d like to ask for opinions.

<big snip>

So I still wonder why this GFCI did not trip during the time I was feeling the shock. I also wonder whether it would trip, if there were a future need.

Any ideas (before I list my unlikely ones)?

I suspect the answer lies within UL943. The standard requires a trip response that follows an inverse time curve where Time = (20/mA)^1.43. At 6ma, this equates to 5595ms; at 10mA up to 2694ms. I, for one, would not want to take 10mA for over 2 1/2 seconds. That's the worst case, but it does show that GFCIs aren't designed to prevent zapping you, just to avoid killing you.

The good news is that GFCIs typically trip much faster than required. Ones I've tested have typically been under 250msec with current in the 6.5 to 6.9 mA range.

 

[charlie b]

Mike, that makes a lot of sense. My memory tells me the shock lasted for about a second, perhaps a bit less. Using your formula, that would limit the shock current to 20 milliamps or so. But that is well into the ?painful, possible loss of muscle control? area. That would explain why I could have felt a very distressing (perhaps ?painful? is too strong a word) shock, without the GFCI having tripped.