Severity of electric shock

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domnic

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The the severity of a electric shock is realted to four elements, current, length of time, path through the body, and ferquency of current,time, where does HZ COME IN TO PLAY ?
 
The higher the HZ the less the current will travel through the body and instead on the outer skin, avoiding vital organ. look up Skin effect.
A high amount of current on a Low HZ will be more fatal, then the same current on a Higher HZ system.
Some one will post more info on this subject for you.
 
AC\DC said:
The higher the HZ the less the current will travel through the body and instead on the outer skin, avoiding vital organ. look up Skin effect.
A high amount of current on a Low HZ will be more fatal, then the same current on a Higher HZ system.
Some one will post more info on this subject for you.
Click to expand...
Skin effect has nothing to do with human skin. At least in the electrical definition. Different frequencies mess with your heart in different ways. Some will stop it, some will put it in A-fib or flutter. Others will be kinder. IIRC this was covered in OSHA 10 or 30.
 
Really always thought the higher hz would play same effect like it does on condutors , less time it has to penetrate between cycles sorry for my inaccurate answer.
 
AC\DC said:
The higher the HZ the less the current will travel through the body and instead on the outer skin, avoiding vital organ. look up Skin effect.
A high amount of current on a Low HZ will be more fatal, then the same current on a Higher HZ system.
Some one will post more info on this subject for you.
Click to expand...
More voltage rather than more current. We made rectifiers at 40,000 A. They were low voltage units - around 40V. According to our safety officer the risk threshold is around 70V
 
Higher the frequency the more often it passes
Zero on sign wave giving you more
Chances to break free. This is way if u get hung up on dc you are not getting off of it without outside intervention
 
IEC-60479-1 is an excellent document. I think the full version can be found via Google.


In short, as frequency increases, the amount of current that can pass through skin also increases (capcitive component). However, this diminishes when skin breaks down.

1630862224978.png

Total body impedance:
1630862265071.png
 
domnic said:
The the severity of a electric shock is realted to four elements, current, length of time, path through the body, and ferquency of current,time, where does HZ COME IN TO PLAY ?
Click to expand...
In the report below, Fig. 18 on pg. 38 (pg. 42 of pdf file) shows the let-go current (above which skeletal muscle control is lost) as a function of frequency. Fig. 20 on pg. 45 (pg. 49 of .pdf) shows the current level required to induce ventricular fibrillation, i.e., uncontrolled contractions of the ventricles, as a function of frequency in dogs.


The organized contraction of the ventricles involves the successive movement of ions across individual cell membranes as each cell triggers the one next to it during the depolarization process (which discharges the -90mV potential built up across its cell membrane during the repolarization interval between heartbeats). An electric shock, if strong enough, can disrupt this organized sequence of cell depolarizations across the heart muscles and cause ventricular fibrillation which will be fatal if not corrected. A defibrillator uses a strong and typically "biphasic" pulse to re-synchronize the phasing of the depolarization and repolarization process within the ventricular cells.

Activation of the ventricular cell depolarization process happens when a membrane channel opens allowing the flow of sodium ions. This channel opening is triggered when an adjacent cell connected by a "gap junction" has previously fired and raises the cell potential from the -90mv resting level to above the -70mV threshold potential needed for it to fire and depolarize.

External currents applied through the body can change the voltage gradients across the cell membranes and therefore interfere with the phases in a normal heart rythm. Fig. 5 of the paper below shows how the current required to initiate a cell depolarization rises as a function of frequency. The current is in 10's or 100's of microamps because this is the current only through the heart cells themselves, and not including that through the rest of the body.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2825110/

Through experimentation, the authors of the paper determined the mechanism causing the increase in current required at higher freqeuencies. In the third paragraph below Fig. 5 they mention:
"At the higher frequencies, the (sodium) channel could not open quickly enough before the stimulus changed phase, necessitating a larger current stimulus to get the cell to fire."
 
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