Low voltage wiring is wiring that does not conduct more than a certain voltage, defined in the United Kingdom as below 50 volts alternating current or 120 volts direct current. It thus does not pose the same degree of risk as higher-voltage systems do.
'Low voltage' is not an official term used by U.S. Occupational Safety and Health Administration standards or regulations. Though the term is not used in OSHA information resources, OSHA lifts restrictions on equipment operating with fewer than 50 volts in select contexts, thus acknowledging the concept of low voltage systems without categorizing or labeling them as such. The restrictions lifted generally involve the risk of accidents causing damage to equipment or personnel.
Systems conducting fewer than 50 volts are sometimes known by electricians as "extra-low" or "ultra-low" voltage systems, with low voltage systems then occupying the range of 50-600 volts. The National Electrical Code still applies to ultra-low voltage systems, even when OSHA standards do not apply.
Despite being called the National Electrical Code, the NEC is not a federally applied standard. Instead, it is voluntarily adopted or legislated into law by state and regional governments, and sometimes amended to suit local concerns. This means that different states may have different NEC standards or may lack NEC standards altogether.