A.C. is said to be four to five times more dangerous than D.C. For one thing, A.C. causes more severe muscular contractions. For another, it stimulates sweating, which lowers the skin resistance. Along those lines, it is important to note that resistance goes down rapidly with continued contact.
We also know that our human bodies conduct electricity and hence when these charges flow through our bodies we experience electric shock. Since both the AC and DC are harmful to us, since the power due to a DC is greater than that of an AC source, a DC shock may be fatal and can kill you.
6 to 25 Milliamps (women) Painful shocks. Loss of muscle control. 9 to 30 Milliamps (men) The freezing current or “let go” range. If extensor muscles are excited by shock, the person may be thrown away from the power source.
Assuming a steady current flow (as opposed to a shock from a capacitor or from static electricity), shocks above 2,700 volts are often fatal, with those above 11,000 volts being usually fatal, though exceptional cases have been noted.
Alternating current at 220V is more dangerous than direct current of 220V .
A.C. is said to be four to five times more dangerous than D.C. For one thing, A.C. causes more severe muscular contractions. For another, it stimulates sweating, which lowers the skin resistance. Along those lines, it is important to note that resistance goes down rapidly with continued contact.
DC Electricity is Safer to Handle
That being said, while both are dangerous, AC electricity is more dangerous to work with due to these reasons: The human body has a higher impedance to DC currents than AC; humans can withstand higher voltages of DC electricity than AC.
Since the DC is easier to shake off, if the current shock duration is 1 second, then the corresponding comparative limit value is 50mA (see Figure 3), then current values ≤ 60V are very safe for human body.
DC current is not used in homes because of the following reasons: First of all, DC is difficult to generate because primarily it is generated by batteries and electrochemical of photovoltaic cells. Power loss during transmission is more in direct current as compared to alternating current.
Second, lightning is a direct current (DC) that would require it to be converted to alternating current (AC) so it could be used for lights and other equipment.
Direct current (DC) electrocution is exceedingly rare, especially in the context of workplace accidents and exposure, where electrical fatality is almost exclusively associated with alternating current (AC).
During the early years of electricity, direct current (shorthanded as DC) was the standard in the U.S. But there was one problem. Direct current is not easily converted to higher or lower voltages. Tesla believed that alternating current (or AC) was the solution to this problem.
Therefore, AC current is more dangerous than DC current because it has a greater magnitude than its RMS value; it directly affects our heart as the frequency of AC current interferes with the frequency of the electric pulses of the heart.
Electric shock
A voltage as low as 50 volts applied between two parts of the human body causes a current to flow that can block the electrical signals between the brain and the muscles. This may have a number of effects including: Stopping the heart beating properly. Preventing the person from breathing.
12V isn't a shock hazard, but it IS a burn hazard.
Even without a short circuit, if you make or break an electrical connection that has a lot of current going through it, the point at which the connection is made can get very hot very quickly and can burn your fingers.
The principle that “current kills” is essentially correct. It is electric current that burns tissue, freezes muscles, and fibrillates hearts. However, electric current doesn't just occur on its own: there must be voltage available to motivate the current to flow through a victim.
The human body feels a shock when the voltage is higher than about 3,500 volts. Walking over a carpet can generate 35,000 volts.
The human body's voltage increases when the right foot rises, and its peak value is 13 V. The human body's voltage decreases and increases immediately to 7 V when the right foot is lowered. The largest human body voltage is 17 V.
This low power level is the reason why low-voltage (<50V) shocks have never been fatal — there is not enough electrical energy available to disrupt bodily functions.
Conversely, 24VDC's main advantage over other voltage levels is safety. No arc flash hazards are present and the voltage is low enough that the shock hazard is almost negligible.
In the USA the two commonly supplied shore-power voltages are 120 Volts (60Hz) AC and 240 Volts (60Hz) AC.
HVDC can expand the energy networks, making them more stable. HVDC is more environmentally friendly than AC, providing more energy per square metre over greater distances more efficiently than AC systems, as well as lower losses and less space requirements.