Low voltage

In electrical engineering, low voltage is a relative term, the definition varying by context.

Different definitions are used in electric power transmission and distribution, compared with electronics design.

IET Wiring Regulations, defines supply system low voltage as: exceeding 50 V AC or 120 V ripple-free DC.

For example, a direct current that is exceeding 1500 V during voltage fluctuations is not categorized as low-voltage.

In electrical power distribution, the US National Electrical Code (NEC), NFPA 70, article 725 (2005), defines low distribution system voltage (LDSV) as up to 49 V. The NFPA standard 79 article 6.4.1.1[4] defines distribution protected extra-low voltage (PELV) as nominal voltage of 30 Vrms or 60 V DC ripple-free for dry locations, and 6 Vrms or 15 V DC in all other cases.