Arizona Constitution Art. XV § 2. “Public service corporations” defined

Section 2. All corporations other than municipal engaged in furnishing gas, oil, or electricity for light, fuel, or power; or in furnishing water for irrigation, fire protection, or other public purposes; or in furnishing, for profit, hot or cold air or steam for heating or cooling purposes; or engaged in collecting, transporting, treating, purifying and disposing of sewage through a system, for profit; or in transmitting messages or furnishing public telegraph or telephone service, and all corporations other than municipal, operating as common carriers, shall be deemed public service corporations.