Cal. Public Utilities Code § 125102

(a) A majority of the members of the board constitutes a quorum for the transaction of business. All official acts of the board require the affirmative vote of the majority of the members of the board present. However, after a vote of the members is taken, a weighted vote may be called by any two members. (b) In the case of a weighted vote, the County of San Diego and each city shall, in total, exercise 100 votes to be apportioned annually based on population. (c) Approval under the weighted vote procedure requires the vote of the representatives of not less than three jurisdictions representing not less than 51 percent of the total weighted vote to supersede the original action of the board. (d) When a weighted vote is taken on any item that requires more than a majority vote of the board, it shall also require the supermajority percentage of the weighted vote. (e) For purposes of subdivision (b), the population of the County of San Diego is the population in the unincorporated area of the county within the area of jurisdiction of the board pursuant to Section 125052. (f) The board shall adopt a policy and procedure to implement this section.