I have some electrical parts that I was planning to reuse, things like laptop chargers and some parts from a printer. I searched google for what's the lethal amount of current and they mention 10ma is lethal. But they didn't mention for what voltage it is lethal. My phone charger outputs 2Amp at 5 volts and I know it's not harmful. So I have these parts that output 24V 0.6Amps and I wanna know if there's a way I can know this will be harmful or not?

In general is there a formula I can use to calculate a threshold amp value for given DC/AC voltage?

  • \$\begingroup\$ Voltage on its own isn't lethal. There's a saying "volts jolt but mils kill". \$\endgroup\$ – Andy aka Jul 18 '20 at 8:04
  • \$\begingroup\$ Does this answer your question? How much voltage/current is "dangerous"? \$\endgroup\$ – JRE Jul 18 '20 at 8:43
  • \$\begingroup\$ @Rohit: There isn't a simple calculation you can do. The question I've linked to goes into some detail about why it isn't simple, and provides some guidelines. \$\endgroup\$ – JRE Jul 18 '20 at 8:45
  • \$\begingroup\$ 36 VDC is deemed safe. People have died from making contact with a 36V helicopter battery. Rare. Not impossible. \$\endgroup\$ – Russell McMahon Jul 18 '20 at 11:43

The formula is very basic Ohm's law:

$$I=\dfrac{V}{R}$$ or $$V=I\cdot R$$

Anyway, the 10mA isn't lethal, a current more than 30mA through the heart may cause permanent damage to heart or infarct.

There is no specific lethal voltage and current, only the recommendation of the max. current that doesn't cause permanent damage. It depends on size of the body, hydration, ..etc.. on what is the body impedance. It also matters how the body is connected to the electrical circuit: hands-foot, head-foot, ... it also differs if you hold the wire with left hand or with right hand.

Generally any DC voltage below 48V is to be considered safe voltage, or AC voltage below 34V.

  • 1
    \$\begingroup\$ It also depends on when the shock hits in terms of the heart cycle... \$\endgroup\$ – Solar Mike Jul 18 '20 at 9:30

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