No certificate of approval shall be issued unless the installation is in strict conformity with the provisions of this chapter, the statutes of the state and unless they are in conformity with approved methods of construction for safety to life and property. The regulations as set forth in the National Electrical Safety Code, as approved by the American Standards Association, and other installation and safety regulations approved by the American Standards Association, shall be prima facie evidence of such approved methods. (Prior code § 16-1-10)