A lot of people think low voltage electricty is not dangerous, but I will prove them wrong.
Current needed to kill you
From this table you can see how many amps of current is needed to kill a human.
| Current(mA) | Effect |
|---|---|
| 1-10 mA | Prickling sensations |
| 10+ mA | Muscle contraction - the person remains "stuck" to the conductor |
| 20 - 30 mA | Muscle contraction can cause respiratory paralysis |
| 70 - 100 mA | Cardiac fibrillation; the heart begins to vibrate and no longer beats at a steady rate. - Dangerous |
| 100+ mA | Cardiac arrest resulting in death |
Resistance of human body
Of whole human body, human skin has the most resistance. Resistance of human body varies from 1 000Ω to 100 000Ω, it depents on wetness of the skin. Resistance of skin can even drop to almost zero if skin is burnt or punctured.
Resistance of human inside is very low because its full of salts and minerals which are good conductors, therefore resistance of human inside can be low as few hundred ohms.
Calculating current
| Voltage | Resistance | Current |
|---|---|---|
| 9V | 3 000Ω | 3mA |
| 9V | 300Ω | 30mA |
| 30V | 3 000Ω | 10mA |
| 30V | 300Ω | 100mA |
From table above you can observe that 9V battery connected to your wet skin wont do anything, but if conductors contact your flesh directly currenct exceeds 10mA what causes you to hold on to conductor and makes more damage to your skin and causes respiratory paralysis.
30V to wet skin causes you to hold on to conductor and as your skin gets more and more damaged, resistance decreases therefore current increases and can go up to 100mA what is lethal.
Special cases
Human body doesnt only have resistance, it has capacitance too. Your skin acts like dielectric between your flesh and metal conductor. Therefore if you connect yourself to AC, resistance of your skin becomes almost zero because capacitors are "shortened out" in AC, which brings you to even more dangerous situations.
Stay safe and dont play with electricty, spread this word and save lifes.