Which One Kills – Current or Voltage and Why? Amps vs Volts

Electrical Technology

Which One is the Fatal, Voltage or Current and Why?

A bad wife or girlfriend won’t kill you, but voltage and current can do so easily at a certain level. That’s why no one should play with electricity (power, voltage, and current) because it can be our friend, but it can also be our worst enemy. If we give it a chance, it will not hesitate to strike.

Before we go in details, I will ask another question. If I kill you with a knife (don’t worry, I won’t but not guaranteed), will you blame the knife or me? Another way, Which is the killer, bullet or gunpowder?. Related to the topic, Which is the killer, Current or Voltage?

Before we delve into the details, I have another question. If I were to harm you with a knife (don’t worry, I won’t, and there’s no guarantee of it happening), would you blame the knife or me? Similarly bullet or gunpowder?, when it comes to the topic at hand, which is the true ‘killer’ current or voltage?

To know the exact reason, we must know the difference between Current and Voltage. As explained in the previous post, voltage is the cause and current is the effect.

Voltage: is the potential difference (a type a force) between two points which causes current to flow in the circuit. It is the force required to move the amount of energy from one point to another.
Current: is the rate of charge flow (electrons) between two points caused by voltage. Voltage is the main cause to push the electrons through a conductor or completed electric circuit.

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To know which is the fatal, voltage or current? Let’s see the following formulas.

V = I x R … (Ohm’s Law)
P = V x I … (Power in DC circuits)
P = V x I x Cosθ … (Power in AC single phase AC circuits)

Where:

As the first formula (or Ohm’s law) shows that voltage is must to flow the current in a conductive material having some amount of resistance as almost all materials having some amount of resistance to the flow of electrons through it.

At the other hand, In I = V / R, current is directly proportional to the voltage, but current is inversely proportional to the voltage in P = VI?

The logic behind this scenario is that some of the quantities remain the same in the first case, while parameters change in the second case. Assuming that the resistance is constant, then:

If the power of the source is constant, the current decreases when voltage increases.
If the power of the source increases, both voltage and current increase, meaning the power is variable.

So the main cause is the voltage and current as an effect is the killer at specific rate for specified period. Current will kill you but some amount of voltage is required to flow that current in the body breaking the human body resistance. In other words, an enough power is required to pass in the human body for proper electric shock.

In short, high voltage with a few micro amperes cause nothing to the human body like in high voltage supplying cathode ray tube in traditional TV set or high static voltage in the comb. on the other hand high current with hundredth of ampere with ten, twenty or thirty or more make nothing to human bodies like electric welding machine as the amount of voltage is not enough to push that level of high current in the human body as there is a path with least amount of resistance as compared to the human body internal resistance. Another example is the car battery having high amperage with low voltage level (12V DC) but if we touch both leads, it won’t electrocute. Therefore enough voltage of hundredth with enough current make electric shock to human bodies because human body like resistor need enough power to pass current.

Keep in mind that the effects of electrical current through the human body vary according to:

The value of the current
The value of the voltage
The time the current flows through human body
The frequency of the supply (50Hz / 60Hz or more / low)
The pathway of the current (dry, wet etc.)
The ability of the person to react (nerve system)

The following level of voltage are considered safe.

AC Voltage

25V (Wet places)
50V (Dry places)

DC Voltage

120V DC

The following tables shows the different values of AC and DC currents in mA and its effect on the human body. Keep in mind that it is the average value and not meant to be same for everyone as it depends on different factors.

AC in mA (50Hz)	DC in mA	Effects on Human Body
0.5 – 1.5	0.4	Perception
1.3	4 – 15	Surprise
3 – 22	15 – 88	Let’s Go (Reflex Action)
22 – 40	80 – 160	Muscular Inhibition
40 – 100	160 – 300	Respiratory Block
More than 100	More than 300	Usually Fatal

Electrical Shock Hazards & Effects on Human Body

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Conclusion about the confusion of which one is hazardous, Current or Voltage?: Current Kills, Not the Voltage. But Voltage is must to drive the Current. I.e. Amperes are responsible for electrocution, Not the Volts.

Warning: Both AC and DC voltages and currents are dangerous. Don’t touch the live wires. In case of electric shock and hazardous effects, try to disconnect the power supply and push back the victim body from the source (keep in mind that you should properly insulated before doing so). Only call the professional and licensed electrician in case of repairing or troubleshooting. In case of emergency, call the local authority for medical help ASAP.

Good to Know:

The average resistance of a human body in dry condition is almost ≈ 100,000Ω while the resistance of a human body in wet condition is 1000Ω.
Also, the voltage above 50V (in dry condition) and 25V (in wet condition) is enough to shock a person. Also, 30 mA (RCDs are set in the UK) is enough for respiratory paralysis while 75-100 mA will cause ventricular fibrillation (rapid & ineffective heartbeat).
Anything higher than 300mA is fatal and kills in seconds. 4.5 to 10A will instantly lead to cardiac arrest, severe burns and finally death.
Overall, it is mainly the eclectic power (a mixture of current and voltage) where voltage (as a pressure) pushes electric current (as a flow of charge) is responsible for electric shock.