(1) Each public utility providing electric service subject to the jurisdiction of the commission shall, at the minimum, maintain its electric utility lines and facilities pursuant to the national electrical safety code as that code is identified in 69-4-201 , MCA, the effective edition of which is designated at ARM 38.5.1010.

(2) The edition of the code applicable at the time of maintenance shall be that in effect by statute or rule at the time of construction of the electric utility line or facility unless, without undue expense, the edition in effect by statute or rule at the time of maintenance can reasonably be complied with.