There is levied and shall be collected from every person, firm, corporation and municipal corporation, including any public utility district, which operates in the city a plant or system of facilities for the generation, production or distribution of electrical energy for hire or sale and/or for the wheeling of electricity for others, a tax in the amount of six percent of the gross revenue derived from the sale of electricity within the city limits; provided, however, that the tax is levied and shall be collected in the amount of two percent only of gross revenues in excess of twenty five thousand dollars from the sale of electricity to a single consumer in any monthly period; and provided further that commencing January 1, 2006, no tax shall be collected on gross revenues in excess of three hundred thousand dollars from the sale of electricity to a single consumer in any monthly period. (Ord. M-3725 §1, 2005; Ord. M-3679 §1, 2004; Ord. M-3292, 1997; Ord. M-1559 §1, 1974; Ord. M-597 (part), 1962; Ord. M-30 (part), 1952; Ord. C-356 §2, 1951)