California Code, Public Utilities Code - PUC § 1702.2

(a) Except as provided in subdivision (b), any funds entrusted to the commission by any person or corporation filing a complaint against a public utility shall be deposited in trust by the commission in the custody of the Treasurer, as specified in Section 16305.3 of the Government Code.

(b) If the amount of the funds entrusted to the commission by a person or corporation filing a complaint against a public utility exceeds twenty thousand dollars ($20,000), the commission may deposit the funds in trust in an insured account with a bank or a federal or state savings and loan association, bearing interest at rates up to the maximum permitted by law. The commission shall pay these funds, together with the interest paid thereon, to the party specified in the commission's order or decision on that complaint.