Refer to http://www.allaboutcircuits.com/vol_1/chpt_3/2.html

The following paragraph conflicts with the review on the same page. See the underlined words. Which is correct?:

How AC affects the body depends largely on frequency. Low-frequency (50- to 60-Hz) AC is used in US (60 Hz) and European (50 Hz) households; it can be more dangerous than high-frequency AC and is 3 to 5 times more dangerous than DC of the same voltage and amperage. Low-frequency AC produces extended muscle contraction (tetany), which may freeze the hand to the current's source, prolonging exposure. DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source. [MMOM]
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AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart. This is why "defibrillating" equipment used by emergency medics works: the jolt of current supplied by the defibrillator unit is DC, which halts fibrillation and gives the heart a chance to recover.
In either case, electric currents high enough to cause involuntary muscle action are dangerous and are to be avoided at all costs. In the next section, we'll take a look at how such currents typically enter and exit the body, and examine precautions against such occurrences.

• REVIEW:
• Electric current is capable of producing deep and severe burns in the body due to power dissipation across the body's electrical resistance.
• Tetanus is the condition where muscles involuntarily contract due to the passage of external electric current through the body. When involuntary contraction of muscles controlling the fingers causes a victim to be unable to let go of an energized conductor, the victim is said to be "froze on the circuit."
• Diaphragm (lung) and heart muscles are similarly affected by electric current. Even currents too small to induce tetanus can be strong enough to interfere with the heart's pacemaker neurons, causing the heart to flutter instead of strongly beat.
• Direct current (DC) is more likely to cause muscle tetanus than alternating current (AC), making DC more likely to "freeze" a victim in a shock scenario. However, AC is more likely to cause a victim's heart to fibrillate, which is a more dangerous condition for the victim after the shocking current has been halted.

 

Yes, it may need some ironing there. Even if mains frequency isn't really high, there's some conflict in the above text.

Do you have any suggestions on the corrected text?
I don't know out of my head at what frequency fibrillation is more likely than tetany.

 

In the first section, aren't AC and DC backwards? DC causes muscle contraction and makes it harder for the victim to let go, AC causes the convulsive reaction that throws the victim. That's what I always learned (and experienced). It also agrees with the review.

 

I will risk the characterization "crappy" for this section. It needs to be much more clear and facts-oriented.