Well duh! But not all electricity is harmful, or is it?!

Well, I guess it could hurt even when it is not too dangerous, so be careful!

But how can electricity be harmful? In low levels, if it passed through your heart or your brain, it can leave damage or death. They say 5mA of current through the heart can cause a cardiac arrest. In high levels, it can badly burn the body inside and out and then possibly cause death.

So electricity is dangerous, but not always. When something is capable of delivering many amps of current, it doesn’t necessarily mean that it will hurt you. Remember:

Voltage = Current x Resistance

So you need high voltage to generate high current. For DC currents, the body resistance through dry skin is usually pretty high, in orders of 100 kilo Ohms. So to create 5mA of current, you will need somewhere over 500VDC. And even then, you need to touch the voltage in a way that the current actually passes through your sensitive parts, I mean your heart for example. You can barley feel a 100V DC through dry skin.

Of course when the skin is wet the resistance drops significantly and lower voltage can hurt too. The tong is a low resistance part of the body. Have you ever put a 9V battery on your tong and see how that hurts? No?? Then you should try it! Don’t worry, this one is safe!

It is very different for an AC current. Human body has a capacitive property, which means as the frequency goes higher it shows smaller resistance towards current and more flows with less voltage amplitude. While you don’t feel anything for a 50VDC voltage, you can badly hurt with a 50VAC, 50 Hertz.

As a crazy engineer, I have touched many different kind of electricity, of course not for fun, but in the line of duty! Please don’t try it yourself and just go with my experience.

– I once made a DC voltage generator and raised its voltage up to 600V slowly and held the wires. It is unbearable at around 300V!

– I have touched 220VAC (European standard, 50Hz) and 110VAC (North American standard, 60Hz) many times and I should say they both hurt pretty much the same. I am guessing 110VAC hurts the same as 220VAC because of its slightly higher frequency. Of course I can’t say I am an accurate hurting scale.

– I have been zapped many times with ESD (Electrostatic Discharge) voltages of between 0V to 25KV. The 25KV stings badly.

– I have touched the ringing voltage on the phone lines. If memory serves right it is 90VAC at 25Hz. It hurts a bit.

Here’s my favorite frame of the video when sparks are hitting my face!