Electricity Effects on people

The human body conducts electricity. Very small currents are harmless and are e.g. B. used in medicine. However, larger currents can lead to injuries and even death. Therefore, humans must fundamentally protect themselves from the dangerous effects of electric current.

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Current in Human body

The human body conducts electricity. Body fluids are responsible for their conductivity. In contrast to metals, the electrical current is conducted by ions. In contrast to metals (first-order conductors ), such conductors are called second-order conductors.

Very small currents in the range from microamps to one milliampere are harmless and are used eg B. used in medicine (eg stimulation current diagnostics and therapy).

Larger electrical currents flowing through the body can injure or even kill people.
The effect of electric current on humans depends

  • the strength of the current through the body,
  • the type of current (direct current, alternating current, high-frequency alternating current),
  • from the current path through the body,
  • on the duration of the action of the electric current.
Danger of Electricity

Caution! High voltage. There is a danger to life.

The most important current paths through the human body are shown in Figure 2. Direct currents and alternating currents that flow over the area of ​​the heart (eg from hand to hand) are particularly dangerous. They can influence the heart’s activity, lead to cardiac arrest and thus death. Larger currents can also cause burns.

Investigations have shown that the human body resistance in the current paths shown in Figure 2 is around 1500 ohms on average. In addition, there is a contact resistance of around 1000 ohms between the skin and the voltage source with which one comes into contact. The average total resistance is thus around 2500 ohms.
If the voltage is 25 V, a current of

I=U/R

I= 25  V / 2 500 Ω

I= 0.01  A = 10  mA

Such a current of 10 mA is not yet life-threatening, but you can usually feel its effects clearly.

Investigations on test persons with alternating current of 50 Hz showed the following typical effects of electrical currents for the hand-hand current path :

2 mAElectricity just noticeable in the palms of the hands
3 mAslight tingling sensation in the palms of the hands, as if the hands were asleep
4.5 mASlight vibration of the hands, pressure in the wrists
8 mAHands become stiff and cramped
15 mAGeneral spasm of the arm muscles reaching up to the armpits is
just possible to let go
16.5 mAComplete cramping of the hands and arms, it is no longer possible to let go, severe pain occurs.
over 40 mAand exposure times of more than 2 seconds:
ventricular fibrillation, death likely with increasing perfusion time.
Table

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