How many volts of electricy can kill a person?

A simple experiment to show voltage as ultimately harmless is to track across carpet then touch metal. The shock that you receive from this can easily exceed 12,000 Volts, and can be in the high 20's. There is no real current to this shock though, and the duration of exposure is also negligible. Current is the amount of charge that passes through a plane, where as voltage represents the difference of potential energy between source and its ground (you in this case would be the path to ground). Current is roughly equivalent to Voltage divided by resistance. Meaning the higher resistance is, the lower the current which is harmful product. Your house (in the United States) provides 110-117VAC at 60 Hz to all of your outlets. What you need to look at here is the 60 Hz. Because 60 Hz so closely matches the pace of the heart, this frequency is HIGHLY dangerous, as when the current passes your heart it can cause fibrilation. Now, if you have ever done any household electric work, you have likely touched a hot wire before and been fine. Most outlets and sources still do not have a ton of current through them. Also, the sudden shock causes you to jolt back minimizing the duration and protecting the heart. Were you to grab and hold on to these wires, you would likely die from it. In avionics, I know that 400 Hz frequency is generally used, and this is far safer to work with, as it is far less likely to cause fibrilation. Higher current sources though will still cook a person in a matter of seconds. With all of this in mind, your question asks what is the lowest amount of volts that can kill you. Because resistance of each persons body is different, the amount of current produced from a voltage source will differ depending on who is touching it, and how they are exposed to it. Were a small child to latch on to an active AC source with even 30-40 Volts, it could be deadly (fibrilation can still occur at lower voltages and cause death). For DC, the voltage would be approximately the same, but the primary path of the current would have to be through the body to be dangerous at all. For an adult, you would be looking at 40-50 Volts.