PELV
PELV (English for “Protective Extra Low Voltage” – formerly also known as safety extra-low voltage; see also SELV) describes a voltage that is set so low(extra-low voltage) that there is no danger from body currents in the event of indirect contact or direct contact that does not cover a large area. If insulation fails, there must still be sufficient protection. In the case of power supply units, this is achieved by galvanic isolation with double or reinforced insulation between the primary and secondary sides.
The rated voltage of a PELV voltage source must not exceed 25 V effective AC voltage or 60 V harmonic-free DC voltage. One side of the PELV circuit must be connected to the protective earth conductor system. However, this does not necessarily have to be done on the power supply unit.
