(1) Except as provided in subsection (2) of this section, the Public Utility Commission may designate by order or rule any commissioner or any named employee or category of employees who shall have authority to exercise any of the duties and powers imposed upon the commission by law. The official act of any commissioner or employee so exercising any such duties or powers is considered to be an official act of the commission.
(2) The commission may not delegate to any commissioner, named employee or category of employees under subsection (1) of this section the authority to:
(a) Sign an interim or final order after hearing;
(b) Sign any order upon any investigation the commission causes to be initiated;
(c) Sign an order that makes effective a rule;
(d) Enter orders on reconsideration or following rehearing; or
(e) Grant immunity from prosecution, forfeiture or penalty.