An authority expressed in general terms, however broad, does not authorize an agent to do any of the following:
(a) Act in the agent’s own name, unless it is the usual course of business to do so.
(b) Define the scope of the agency.
(c) Violate a duty to which a trustee is subject under Section 16002, 16004, 16005, or 16009 of the Probate Code.
(Amended by Stats. 1988, Ch. 113, Sec. 5. Effective May 25, 1988. Operative July 1, 1988, by Sec. 23 of Ch. 113.)