A public service company must not dispose of any property necessary or useful to perform its public duties unless it first applies for, and obtains, written authority from the commission.

Necessary or useful includes all property except items that:

(1) Are substituted with or replaced by items of equal or greater value or usefulness;

(2) Are surplus and unneeded assets for which full value is received;

(3) Are obsolete; or

(4) Are excluded from the public service company's rate base by commission order, or otherwise.

The public service company must file an application for commission determination that the property is not necessary or useful, prior to disposing of such property, if the property to be disposed of has a market value that exceeds the greater of .1% of the public service company's rate base (for the applicable utility service) last established by commission order, or $20,000.