All electrical equipment installed or used shall be in conformity with the provisions of this chapter, the statutes of the state and any orders, rules and regulations issued by authority thereof, and with approved electrical standards for safety to persons or to property. Unless by this chapter, by a statute of the state or any orders, rules, or regulations issued by authority thereof, a specific type or class of electrical equipment is disapproved for installation and use, conformity with the standards of Underwriters' Laboratories, Inc., shall be prima facie evidence of conformity with approved standards for safety to persons or to property. (Prior Code, Section 12 in part)