In electrical engineering, alternating voltages (AC) up to 50 volts effective value and direct voltages (DC) up to 120 volts are referred to as low voltage, colloquially also low voltage or low current. It is a subrange of low voltage. The European Low Voltage Directive therefore also applies to the upper range of the low voltage (AC over 50 volts effective value and DC over 75 volts). For voltages below 25 volts AC or 60 volts DC, protection against contact can be dispensed with altogether; these voltages are also considered harmless to animals and children.
A distinction is made between: SELV (formerly "safety extra-low voltage") is a small electrical voltage which offers special protection against electric shock due to its low height and the insulation compared to circuits of higher voltage. Devices operated with SELV which themselves do not generate higher voltages are designated protection class III in accordance with DIN EN 61140 (VDE 0140-1).
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