In 1882, the National Fire Insurers Board (NBFU) also adopted early safety regulations. In 1893, the National Insurance and Electricity Association began to try to unify the different electrical installation standards and specifications of various states, and proposed a national coding standard for electric lights and power supply installations for building wiring.
The first National Electrical Code (NEC) was proposed by NBFU in 1897, and it also ignored the standardization of wire color issues. Later, in 1928, NEC was updated and revised. One of the requirements was to establish a specification for the color of the ground wire, which was later white or natural gray, and it was also forbidden to apply these colors to the live wire and the neutral wire.
