Electrocution Statistics

[big john]

Recently, I've found myself encountering more and more people who are absolutely ignorant about the hazards electricity presents. In trying to dispel common myths (Electricity, being lazy, takes the shortest path to ground. :roll: ) and explain common dangers, I usually find myself saying the following:

"At some point during their lives, many people have received a shock from a receptacle or light fixture. They come through the shock unscathed, maybe noting that it didn't even hurt them that badly, and they develop the misconception that 120 volts presents no real hazard. This is absolutely false."

Sometimes even right after I say that, I will have someone relate a story to me about how they don't think 120V is dangerous because they used to put paper-clips in receptacles when they were younger, and they survived. I don't understand what it takes to get through to these folks!

I've always heard that more people in the U.S. are electrocuted by 120V than any other voltage, which makes sense because of it's prevalence. Try as I might, though, I can't find any statistics to back me up.

Can any of you point me to any hard statistics or references I can use as ammunition in the fight to combat this ignorance? I would greatly appreciate it.

Thanks.

-John

[ January 08, 2004, 10:24 AM: Message edited by: big john ]

 

[pwhite]

Re: Electrocution Statistics

several posts have been made in reference to current across the body and its effects. i cannot remember what post it was. i know one is in the archives. you may want to do a search. maybe someone else will post a better answer for you.

 

[templdl]

Re: Electrocution Statistics

How much electrical current?
Table applies to 60Hz current passing from one arm to the other:

Current in mA Effect to humans
1 to 5 tingling sensation
5 to 8 pain
8 to 20 involuntary muscle contraction
> 20 paralysis, can't breathe, pain
80 to 1000 ventricular and heart fibrillation
>1000 heart stoppage, burns, defibrillation
Current Involved in Electric Shock
The electric current in amperes is the most important physiological variable which determines the severity of an electric shock. However, this current is in turn determined by the driving voltage and the resistance of the path which the current follows through the body. One difficulty in establishing the conditions for electrical safety is that a voltage which produces only a mild tingling sensation under one circumstance can be a lethal shock hazard under other conditions.

Will the 120 volt common household voltage produce a dangerous shock? It depends!
If your body resistance is 100,000 ohms, then the current which would flow would be:
I=120v/100,000ohms=.0012a or 1.2ma which would be about the threshold of perception so it would produce only a tingle.
But if are sweaty and barefoot, then your resistance to ground may be as low as 1000 ohms. Then the current would be:
I=120v/1000ohms=.12a which may seem very little by is 120ma. As you can see by the chart about this is big time trouble, ventricular and heart fibrillation and death.

The severity of shock from a given source will depend upon its path through your body.
Yes,120v can be dangerous. But, change the voltage to 480v in the first example @ 100,000ohms and now you have a current of .0048a or 4.8ma.

 

[wyedelta]

Re: Electrocution Statistics

Ya milli amp is disastrous to human.Electrocution will depend how your body will be in contact with earth(ground: say ground conductor/metal parts or equiptment parts).Our body offer different resistant depending on the condition: if our hands/body is wet it offer less resistant and becone more conductable to current flow.as ohm law stated: voltage is directly propotional to current therefor as voltage increase the current(resistant: constant)
This is the reason why we put DANGER HIGH VOLTAGE and not DANGER high Current because little current make death not the high pressure(voltage).
Some poster saidON'T MEDDLE WITH ELECTRICITY which is true.
Good Luck hope you win your battle.
ALWAYS THINK SAFETY FIRST... before other factors.

 

[wyedelta]

Re: Electrocution Statistics

apology:correction, as voltage increase the current increase (resistant; contant).

Many Thanks.

 

[pwhite]

Re: Electrocution Statistics

templdl,

where did your information come from?
i would like to get a copy

 

[tom baker]

Re: Electrocution Statistics

When I was in the US Navys Machinist Mate A school, we watched a movie "110 volts-your deadly shipmate". The point being that 110 is more dangerous than other voltages as we take it for granted.

 

[roger]

Re: Electrocution Statistics

Pwhite, you can print this information from this page

Isn't it amazing how some people don't think 120 volts is dangerous, and the scariest part of this thinking comes from those associated in this trade.?

Roger

[ January 12, 2004, 11:13 AM: Message edited by: roger ]

 

[brian john]

Re: Electrocution Statistics

The 120-volt killer is there, BUT the one thing I find scary among electricians is thinking 480/277 vac is 208/120. and treating troubling shooting , Ground Fault operations of a switch on a 480/277-vac switchboard as nothing more than a tripped CB. My firm has been involved in a few 120 accidents where someone was killed. We have been involved in numerous deaths a quite a few serious injuries involving 480/277 vac. Most of these were due to a disrespect or lack of understanding how to handle faults, in particular 408/277 vac. In most cases this lead to an arcing ground fault and the catastrophic results.


Treat it all as dangerous, with respect, with caution, and USE a tester no matter what anyone tells you.

 

[templdl]

Re: Electrocution Statistics

Yes, 120v should still be treated with respect. The illustration shows that under a given condition where 120v my cause a mild shock but would cause a fatal shock at a higher voltage. But this is an ideal example. The conditions out in the field are all over the map and are never to be considered as ideal. To say that 120v is safer than 208 or 480v would be foolish because it all depends upon your resistance which you never can be certain of what it may be in a given situaltion.