All electric signs shall be approved and labeled as conforming to the standards of the United States Bureau of Standards, the Underwriters' Laboratories, Inc., or other similar institution of recognized standing. The full number of illuminating elements thereof shall be kept in satisfactory working condition or immediately repaired or replaced. Signs that are only partially illuminated shall meet all electrical requirements for that portion directly illuminated. All electric signs shall have a disconnect switch located in accordance with the provisions of this title and the National Electrical Code as adopted by the city council. (Prior code § 3.06.126)