Can 10-100mA kill a person / be deadly? [duplicate]

Question

According to various sources something as little as 0.01A = 10mA can be painful, at 0.1A = 100mA you can expierence *

1. "ventricular fibrillation of the heart".
2. "an uncoordinated twitching of the walls of the heart's ventricles which result in death".
3. "As well as other painful things such as extreme breathing difficulties, Severe Shock, Muscular paralysis ...". *

How is that true? I've worked with an arduino and LEDs, LED Strips etc for quite a while yet never heard that 10mA can be painful let alone 50-100mA deadly.

Answer 1

First off, its voltage not current that kills (because you have to bypass the skin). The actual mechanism is current once you get under the skin.

The minimum current a human can feel depends on the current type (AC or DC) as well as frequency for AC. A person can feel at least 1 mA (rms) of AC at 60 Hz, while at least 5 mA for DC. At around 10 milliamperes, AC current passing through the arm of a 68-kilogram (150 lb) human can cause powerful muscle contractions; the victim is unable to voluntarily control muscles and cannot release an electrified object.[11] This is known as the "let go threshold" and is a criterion for shock hazard in electrical regulations.

Source: https://en.wikipedia.org/wiki/Electrical_injury

Your not getting 10mA through your heart when you are playing around with electronics or low voltage <60V. Skin is more than 10k (as much as 100k), to get 10mA through 10k is at least 100V. If you have dry skin, it is much higher.

Per IEC directives Low voltage is lower than 50V

In the European Union, the Low Voltage Directive defines low voltage starting from 50 V AC, and 75 V DC. The directive only covers electrical equipment and not voltages appearing inside equipment or voltages in electrical components. IEC 60364 defines it as 50 V AC and 120 V DC.

Source: https://en.wikipedia.org/wiki/Extra-low_voltage

The body has resistance to current flow. More than 99% of the body's resistance to electric current flow is at the skin. Resistance is measured in ohms. A calloused, dry hand may have more than 100,000 Ω because of a thick outer layer of dead cells in the stratum corneum. The internal body resistance is about 300 Ω, being related to the wet, relatively salty tissues beneath the skin. The skin resistance can be effectively bypassed if there is skin breakdown from high voltage, a cut, a deep abrasion, or immersion in water (Table ​(Table2).2). The skin acts like an electrical device such as a capacitor in that it allows more current to flow if a voltage is changing rapidly. A rapidly changing voltage will be applied to the palm and fingers of one's hand if it is holding a metal tool that suddenly touches a voltage source. This type of contact will give a much greater current amplitude in the body than would otherwise occur.

Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2763825/

Answer 2

A circuit that is drawing 10mA or 50-100mA is quite a bit different than a circuit that could push that much current through you.

Figure out what the resistance of the human body is, then calculate how much voltage you would need to force that much current through that resistance. You will quickly see how your arduino is incapable of forcing even 1mA through your body.

Remember, just because something can source 10mA, doesn't mean that it can force that current into anything.

Answer 3

To answer your question, you should be safe for most electronic work, but it is good safety practices to respect all electric circuits and take fundamental safety precautions.

The amount of current a person can handle depends upon many factors. Current quantity, current type, body mass, broken skin, path and length of contact time, etc.

Many similar charts exist. From Science online - Benefits and dangers of electricity

The only scientific study I know of is Charles Dalziel, 1961 (Inventor of the GCFI). Ultimately, this is where the 100mA 60Hz AC and 500mA DC comes from.

As can be seen from the chart DC levels are 3-5 times safer than 60Hz AC.

The first 5 rows are based upon human tests (check out pictures at end of report), while the last is estimated from experiments on dogs. It would be highly unethical to do these tests today.

Fibrillation (100mA-200mA) can be deadly because it sets the muscles of the heart pumping randomly requiring defibrillation as the only way to restart the heart. A higher current will cause serious injuries but the heart/lungs may start once the person is removed from the shock hazard.

Even currents as low as 16mA 60Hz AC and 76mA DC can cause unconsciousness and death if the exposure is long enough as the individual is frozen to the circuit. Your brain, hearts and lungs work, but you cannot let go. All of the muscles of your body are contracted. Think really, really good frozen tag.