“It’s the current that kills, not the voltage.” This phrase gets thrown around a lot whenever someone mentions electrocution--more so with the utterance of high voltages. Yet, this is far from the truth.
Ohm’s Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. In other words, when there is high current, there must also be high voltage. An analogy of a pen can be useful to understand this: while it is the ink from a pen that makes up letters, it’s ultimately the pen that brought the ink to the paper in the first place. Similarly, the voltage is what caused the current flow, and thus electrocution, to happen in the first place.
Now, such confusion with voltage and current is understandable. A supposedly high voltage source set to deliver a little amount of current does, indeed, give off less electricity. It becomes problematic, however, when one draws from this that the voltage doesn’t matter, only the current.
The ‘high voltage’ in this context is merely the voltage without load; as in, with a power supply set to deliver a certain amount of current, the voltage might not continue to be high. With a current-limited power supply and a resistance value not high enough to warrant maintaining the voltage, the voltage drops. The statement that it’s the current that kills, not the voltage, uses the voltage without load as a strawman to the voltage that matters, the voltage under load. If you want to have a high amount of current flowing through anything, you need high voltage. You can’t have a lot of current flowing without also having a high voltage under load.
One another piece of evidence that supports the claim is the Occupational Hazard And Safety Administration(OSHA)’s listing of factors of electrocution severity. The listing tells us that three factors determine the severity of electric shock: the path of the current, the amount of current, and the time of exposure to electric current. None of them directly supports the significance of voltage. There are two different ways to address this.
To begin with, the listing does reinforce the significance of voltage, only indirectly. The relationship between current and voltage established tells us that it would be wrong to say that only current matters when clearly, they accompany each other in all cases.
Aside from that, the OSHA-listed factors for severity of shock give us an important insight: time also plays a factor in determining the severity of shock. The longer you are exposed to electric shock, the more fatal it will be. In other words, the severity of electrocution is proportional to both the time and the current. Current’s unit is ampere (representing charge per second), and time’s unit is seconds. The severity of electrocution, being a product of both current and time, would thus represent charge. Within this system, an infinitesimally short time of exposure would give us electrocution with virtually no severity, no matter the current. Thus, if one was to be punctilious, it would be more accurate to say that it’s the charge that kills, not the voltage nor the current.
Now, I’m not asking you to go around telling everyone that it’s the charge that kills, not the voltage nor the current: that’s wrong, for one, and that’s long, for another. All that I want you to take from this article is that, yes, the voltage does matter, and no, saying “it’s the current that kills, not the voltage” is wrong.
Works Cited
ElectroBOOM. (2018, Feb 13). 7 MILLION VOLT TASER (stun... thingy)!!! [Video]. YouTube. https://youtu.be/DOMs7mYm_zs
ElectroBOOM. (2014, Mar 10). Which is the Killer, Current of Voltage? [Video]. YouTube. https://youtu.be/XDf2nhfxVzg
National Safety Council. (2018). Introduction to Electrical Safety. https://www.osha.gov/sites/default/files/2018-12/fy07_sh-16610-07_01_pg-module_1.pdf
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