(a) When an item of radio-telephone utility plant is retired, account 104, Accumulated Provision for Depreciation of Radio-telephone Plant, shall be charged and the appropriate plant accounts shall be credited with the entire recorded original cost of plant retired regardless of the amount of depreciation which has been accumulated for this particular item of plant, except as provided in subdivision (b) which follows. Account 104, Accumulated Provision for Depreciation of Radio-telephone Plant, shall also be charged with the costs of removal of retired plant, and shall be credited with the salvage value, sales price or other amounts recovered from plant retired.

(b) In rare instances, the unexpected early retirement of a major unit of property which would eliminate or seriously deplete the existing accumulated depreciation may require accounting treatment which differs from that described in subdivision (b) above. In such instances the commission may authorize or order the loss on retirement, less any tax savings, to be charged directly to account 413, Extraordinary and Delayed Items—Net, or to account 117, Deferred Debits, and amortize in future periods. Such accounting treatment shall be used only when specifically authorized or directed by the commission.