What is the standard for AC electrical wiring?

Electrical codes arose in the 1880's with the early commercial introduction of electrical power, since many conflicting standards existed for the selection of wire sizes and other design rules for electrical installations. Regulations may be set by local (city, provincial/state) legislation, perhaps by amendments to a model code produced by a technical standards-setting organization, or by a national standard electrical code. The intention of wiring safety codes is to provide technical, performance and material standards that will allow efficient distribution of electrical energy and communication signals, at the same time protecting persons in the building from electric shock and preventing fire or explosion.