Extra-low Voltage

Extra-low voltage (ELV), in electricity supply, is one of several means to protect against electrical shock. The International Electrotechnical Commission and its member organizations define an ELV circuit as one in which the electrical potential of any conductor against earth (ground) is not more than either 25 volts RMS (35 volts peak) for alternating current, or ripple-free 60 volts for direct current under dry conditions. Lower numbers apply in wet conditions, or when large contact areas are exposed to contact with the human body.

The IEC defines three types of extra-low-voltage systems (FELV, PELV,and SELV), which are distinguished by their successively more restrictive safety properties.