The board of supervisors in any county in which the public administrator or guardian receives a salary in lieu of fees may, in addition to any other revolving fund, establish a revolving fund to be used by the public administrator and a revolving fund to be used by the public guardian in paying the respective fees, expenses, and charges incurred by them: (a) in securing the possession or protecting the assets of any estate, or (b) for the purpose of securing letters of administration, or letters of guardianship or conservatorship, in any estate in which the public administrator or guardian has no funds for the payment of such fees, charges, or expenses but anticipates securing sufficient assets to reimburse the county for such amounts, or (c) where accounting convenience would be served by making a single payment on behalf of several estates and funds are available for immediate reimbursement of the fund by cash transfer. When the offices of public administrator and public guardian are held by the same person, one revolving fund may be established to serve the purposes of both offices as provided herein.