Cal. Public Utilities Code § 125521

Any question which may arise with respect to whether a majority of employees in an appropriate unit desire to be represented by a labor organization shall be submitted to the Public Employment Relations Board. In resolving those questions of representation, including the determination of the appropriate unit or units, petitions, and the conduct of hearings and elections, the board shall apply the relevant federal law and administrative practice developed under the Labor Management Relations Act, 1947, as amended, and, for this purpose, shall adopt appropriate rules and regulations. The California State Mediation and Conciliation Service shall administer any rules and regulations and shall provide for a prompt public hearing and secret ballot election to determine the question of representation and shall certify the results to the parties. Any certification of a labor organization to represent or act for the employees in any collective-bargaining unit shall not be subject to challenge on the grounds that a new substantial question of representation within the collective-bargaining unit exists until the lapse of one year from the date of certification or the expiration of any collective-bargaining agreement, whichever is later, except that no collective-bargaining agreement shall be considered to be a bar to representation proceedings for a period of more than two years.