In regulating the rates of any public utility subject to the provisions of this rule, the Commission shall, on hearing after reasonable notice, ascertain and fix the rate base of the property of the public utility in such a manner as to be fair both to the public utility and to the consumer, when the same is relevant or material to the exercise of the jurisdiction of the Commission. The Commission shall make readjustments from time to time, and ascertain the cost of all new construction, extensions and additions to the property of every public utility.
39 Miss. Code. R. 1-21-100