Like power system frequency, voltage has to be kept within a set range for the power system to work properly and safely. If voltage is too high, equipment can be damaged or “fried”, and if it is too low, equipment can operate poorly or stall.
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.
Since voltage is only a measurement of pressure, there needs to be enough electrons to flow to be dangerous. With enough pressure and flow (amps) an electrical circuit can become dangerous. Any circuit below 50 volts will not have enough electrical pressure to push enough current through your body to cause harm.
It is often more efficient to use higher voltage and lower current. Wires often have an ampacity rating, which is how much current they are rated to handle.
Volts, or voltage, are units of measurement showing the force, or how strongly electrons are pushed through a wire or electrical cable. Volt Analogy: Just like pressure forces fluid through a pump hose, voltage pushes electricity through a wire.
It's The Current That Kills
The real measure of shock's intensity lies in the amount of current (amperes) forced though the body, and not the voltage. Any electrical device used on a house wiring circuit can, under certain conditions, transmit a fatal current.
120V AC Power has a reduced chance of producing a terminal electrocution should one occur. 240V power divides the single-phase electricity into two separate 110V conductors that share a common neutral wire or ground. This allows for a more efficient transfer of power. Power is equal to voltage times current.
It is sometimes suggested that human lethality is most common with alternating current at 100–250 volts; however, death has occurred below this range, with supplies as low as 42 volts.
A touch voltage of 50 V AC (1-1000 Hz) or 120 V DC for long shock duration (> 3 s) should not be exceeded in healthy adults otherwise a life-threatening condition may occur. For children and livestock the touch voltage is limited to 25 V AC or 60 V DC.
Voltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. In brief, voltage = pressure, and it is measured in volts (V).
High voltage has higher potential energy than low voltage. Low voltage has lower potential energy than high voltage. High voltage is typically used to power large devices, while low voltage is usually used to power smaller devices.
Although Edison's preference for DC was eventually proven to be ineffective for power transmission over long distances, safety concerns about Tesla's higher voltage (admittedly fuelled by a PR campaign led by Edison, which included electrocuting a live elephant), led the US to adopt Edison's lower voltage, resulting in ...
The human body feels a shock when the voltage is higher than about 3,500 volts. Walking over a carpet can generate 35,000 volts. The Electrostatic Discharge (ESD) from this voltage can cause pain. The discharge is not life threatening but it still hurts.
Current does not exist without voltage, as voltage is the main cause to flow current except theoretical superconductor.
Dr. Michael S. Morse, a professor of electrical engineering at the University of San Diego, explains that while 10,000 volts can be life threatening in certain circumstances, it's possible for something to have 10,000 volts behind it and be relatively harmless.
Weather.gov > Safety > How Powerful Is Lightning? A typical lightning flash is about 300 million Volts and about 30,000 Amps. In comparison, household current is 120 Volts and 15 Amps.
High voltage currents of 500 V and more can cause deep burns, while low voltage currents consisting of 110–120 V can result in muscle spasms. A person can get an electric shock through contact with an electric current from a small household appliance, wall outlet, or extension cord.
The human body has a higher impedance to DC currents than AC, so this means that humans are able to withstand the effects of an electric shock arising from DC exposure much better than when exposed to AC.
Electical current can produce extremely hazardous situations, 480 volts can cause injury or death.
The TASER energy weapons use a peak voltage of 50,000 volts so that the electrons can be propelled across a 2 inch air gap.
At 1,000 volts, Current = Volts/Ohms = 1,000/500 = 2 Amps which can cause cardiac arrest and serious damage to internal organs.
Limiting current flow in the human body to safe levels is entirely dependent on the resistance of the short-circuiting jumper. To achieve this safe current level the voltage across the human body must not exceed 100 volts.
Now, historically speaking, one of the main reasons why the US stuck with 120V as its standard power supply largely has to do with the fact that it was initially tied to carbon filament lighting.
220V is the older specification. People often refer to 220V even though the voltage has gradually increased over the years. Plenty of brands or manufacturers split the difference on the box or product label with, 115/230volts vs 110/220 vs 120/240.
Cost was the main reason Europe went with 220 volts (now 230). Counterintuitively, higher voltages allow the use of thinner wire, meaning less copper in the early days of power lines. Power companies could save money on wire by using 220 volts rather than 110.