I'm using a 400W PC power supply that is able to deliver at 12V 12 Amperes and 15 Amperes (i' m not sure why there are 2 values). I have connected 3 simple (disk drive) DC motors in parallel and when all of the three run, I get 0.12 Amp on the multimeter. I calculate the watts are 1.44 Watts. When i forcibly stop these with my finger the current jumps to 0.7 Amps (8.4 Watts and more) and growing (the potentiometer i use to control current starts smoking). Now i read that 90mA are able to produce pain, and at 500mA it could be lethal. Can someone advice me by providing some example how i can electrocute myself with such a circuit.
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\$\begingroup\$ Don't worry about it. Everything below 48VDC is considered to be safe. \$\endgroup\$– user125002Commented Feb 13, 2017 at 12:21
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\$\begingroup\$ So the resistance of my body/skin will always protect me with such low voltages? \$\endgroup\$– John AmCommented Feb 13, 2017 at 12:22
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\$\begingroup\$ I won't say 'always' but the risk is a lot less with voltage below 48VDC. \$\endgroup\$– user125002Commented Feb 13, 2017 at 12:26
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\$\begingroup\$ Ok, thanks. So it depends on humidity of the skin, cuts and the position electricity is applied? (i.e. across the chest) \$\endgroup\$– John AmCommented Feb 13, 2017 at 12:28
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\$\begingroup\$ You got it. With 12V there's no way to get hurt unless you lick the wires or plant some electrodes under your skin. We are basically bags of water, but the bag is not a good conductor. \$\endgroup\$– Vladimir CraveroCommented Feb 13, 2017 at 13:01
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When i forcibly stop these with my finger the current jumps to 0.7 Amps (8.4 Watts and more) and growing (the potentiometer i use to control current starts smoking). Now i read that 90mA are able to produce pain,
When you stop the motor, the current doesn't increase because it is flowing through your body. It increases because the motor's stall current is higher than its free-running current.
You shouldn't expect to experience electrocution from this, because no current is flowing through your body (or at least, you haven't told us anything that would make us think there is current flowing through your body).
answered Feb 13, 2017 at 16:27
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\$\begingroup\$ Hm, I know that by stopping the motor i didn't touch any live connection. I guess by stopping it by physically touching the shaft the resistance of the motor get's bigger and the power supply provides more amps \$\endgroup\$– John AmCommented Feb 13, 2017 at 16:52
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\$\begingroup\$ Read the linked Q&A. (Also, if the resistance were to increase, the current draw would decrease, not increase) \$\endgroup\$ Commented Feb 13, 2017 at 16:54
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\$\begingroup\$ Ok, i will read the articles \$\endgroup\$– John AmCommented Feb 13, 2017 at 16:54