Electrical – Can a switching power supply kill you

electricitypower supplysafetyvoltage

I'm curious about one thing. Can a switching power supply with 24V – 4.5A output can kill you if you touch its outputs directly?

As I know, just a 100mA may kill you too, so is it safe to use switching power supply without using any safety equipment or what should I care about?

Best Answer

The thing that is dangerous for the human body is current. While its effect depend on path (though heart or not), duration of the exposition and frequency (in your case DC) in general currents above 1 A are considered deadly.

enter image description here

  • AC-1 zone: Imperceptible

    AC-2 zone: Perceptible

    AC-3 zone: Reversible effects: muscular contraction

    AC-4 zone: Possibility of irreversible effects

    AC-4-1 zone: Up to 5% probability of heart fibrillation

    AC-4-2 zone: Up to 50% probability of heart fibrillation

    AC-4-3 zone: More than 50% probability of heart fibrillation

Source: https://www.electrical-installation.org/enwiki/Protection_against_electric_shock

On the other hand you have to consider that the human body-resistance is voltage dependent (higher voltages = lower body resistance).Below 25 V it is around 60 kOhm. In general, DC voltages below 120 V are not considered deadly, that’s why you can hold a battery with your hands and no current will flow through you, but if you short circuit a battery you can create high currents indeed.

Long story short: the 24 V output of your power supply won’t kill anybody.