Orders of the administrator shall be served upon all parties to the respective proceedings and shall become effective thirty (30) days after the service. Any of the parties to any hearing before the administrator may, upon proper petition, be granted a rehearing. The administrator shall prescribe rules and regulations governing the rehearing. If any rehearing is granted within thirty (30) days after the issuance of an order, then the order shall not become effective until thirty (30) days after the determination of the administrator following the rehearing proceedings.