[TriLUG] On Electrocution

[Brian via TriLUG]

Pete,

It's clear that I went off half-cocked and communicated something I did 
not intend to, and I am deeply apologetic.  I have only the highest 
respect for you and your expertise.  I humbly ask for your forgiveness.

Sincerely,
Brian

On 4/23/20 12:18 PM, Pete Soper via TriLUG wrote:
> Did you happen to read the context of my comment? Twelve volt batteries? 
> Heat, fire risk? Think for about an extra 20 seconds before you make 
> somebody look like an idiot. I have heart rhythm issues and wear a 
> single rubber glove any time I'm dealing with much over 40 volts, 
> specifically to limit the current that has a chance to pass through my 
> chest. And I think I'm one of the folks in this area who propagated the 
> (real, documented) "look at me as I put sharp VOM probes into my fingers 
> and kill  myself" story. Sheesh.
> 
> -Pete
> 
> 
> On 4/23/20 12:06 PM, Brian via TriLUG wrote:
>> On 4/18/20 1:55 PM, Pete Soper via TriLUG wrote:
>>> Current can be just as dangerous as voltage. 
>>
>> It's current that kills you.  Voltage is only the "potential" to 
>> create current; nothing happens until the electrons start moving. A 
>> 12-V car battery can easily melt a large wrench but won't hurt you if 
>> you touch the terminals*.  A nine-volt battery with subdermal contact 
>> can be fatal.
>>
>> i.e. be very careful with your high-range ohmmeter if it has 
>> insulation-piercing probes!
>>
>> And since we're on the subject:
>>
>> First, always be careful with any power source.  But with that said:
>>
>> DC is relatively safe up to some hundred volts in brief contact with 
>> unbroken dry skin.  Dry skin has a relatively high resistance (on the 
>> order of 100 kOhms).  Note that for many of us sweaty-palmed types, 
>> our skin is actually rarely really "dry." Also, resistance is 
>> inversely proportional to contact area, so a larger contact patch 
>> means lower resistance.  So, be careful.
>>
>> Low-frequency high-voltage AC (e.g 60 Hz "house current") is extremely 
>> dangerous, as it will capacitively couple right through your body and 
>> kill you dead.  So, be careful.
>>
>> High-frequency high-voltage AC (several thousand Hz, e.g. a tesla 
>> coil) is much less dangerous; although it can still capacitively 
>> couple through your skin, the "skin effect" will keep current flow 
>> around the perimeter of your body, mostly away from your heart. It'll 
>> still burn and damage you badly, but most likely in a nonfatal way. 
>> So, be careful.
>>
>> See https://en.wikipedia.org/wiki/Electrical_injury for more gory 
>> details.
>>
>> And be careful!
>>
>> :-)
>>
>> -B
>>
>> * - with dry hands