NFPA 70, “National Electric Code“, establish the minimum requirements for the safe installation of electrical wire and equipment. Also known as “NEC”, this code was published originally in 1897 and is updated each 3 years (2008 the latest); “NEC” is approved as a standard by the “The American National Standards Institute” (ANSI).
“NEC” is composed by nine chapters that includes purpose, scope, enforcement, rules and information in regards installation; it’s first four chapters includes voltage, connections, brands, circuits, protection and wire materials as well as equipment; the following three chapters cover special high risk occupations and multi-persons, special equipment as signals and machinery as well as special conditions of emergency equipment, alarms, etc.; Chapter eight is focus on telephone communication systems, radio, TV, etc.; finally, on chapter nine is presented all the information from conductors tables, wire, properties of conduit, etc.
Several “NEC” requirements referred to materials “listed” or “labeled”, which means that they are designed, manufactured, tested inspected and marked according to requirements of the agency who listed them. To be listed the material has to fulfill with testing and requirements such as the ones defined by Underwriters Laboratories (UL) and FM (Factory Mutual), which are laboratories approved for this purposes.