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I know that there is a lot of information regarding the dangers of life-threatening levels of electricity, but I have not seen much about the dangers of low voltages of electricity. For example, I know that low levels of electricity won't immediately kill, but are there any long terms health effects that can come about from exposure to it? As an example of what low voltage is and for how long I would say 2V 30mA for an hour.

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There is an adage in electrical safety that "It is not the voltage that kills you, it is the current". This was investigated at Skeptics.SE. A review of literature regarding electrocution suggests 0.06 A to 0.07 A is fatal. That said, because of Ohm's law, voltage does play a role. Ohm's law says that V=IR, where V is voltage, I is current, and R is resistance.

This analysis measured R for the human body under various conditions (dry, damp, and with a metal ring) and calculated the various voltages needed to get lethal currents based on 17 mA across the chest being lethal. With clean dry skin you would need a voltage of 20 kV while with damp skin you need 340 V to kill you. If you are in contact with metal (e.g., wearing a ring), lethal currents can be generated at as low as 17 V. Even in the worst case scenario of a foot immersed in a conductive liquid with a total resistance of 100 Ohm, would mean that you would require 1.7 V to get a lethal current.

With a 2V, 30 mA, AC power supply, under the right (or wrong) conditions, you could deliver an immediately lethal shock in excess of 17 mA across the chest. If we assume 100 Ohm is the lowest possible resistance, despite the 30 mA source, we are limited to 20 mA at 2 V. The exact impact of 20 mA will depend on the frequency of the source (AC and DC are different and 60 Hz AC is different from 10 kHz AC). With 20 mA at 60 Hz, you would probably lose voluntary muscle control and have pain (possibly sever) and would probably begin experiencing difficulty breathing.

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  • This answer does not mention AC vs DC. It does not mention that the path of the current is also important. 100A running through your finger will cook it, but won't kill you. The conclusion also doesn't follow logically if you say 60mA is the 'lethal threshold' then 30mA should not be lethal. – jiggunjer Jun 11 '15 at 16:29
  • @jiggunjer I tried to clean it up. I agree there are a lot of factors. Standing in a bucket of conducting liquid may not be the use case the OP was considering, but I started with the worst case. I have now added a less than worse case condition. – StrongBad Jun 11 '15 at 16:40
  • @scottb - Please do not answer in comments. An actual answer, though, with references, would be greatly appreciated. – anongoodnurse Jul 12 '15 at 0:10

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