(1) Parties to a proceeding shall include the applicant, petitioner, or complainant, if any; the affected utility company or certificate holder (even if not the applicant or petitioner); trial staff; appearing agencies; and other persons permitted by statute or regulation or by the presiding officer to intervene.

(2) In cases having numerous parties, the presiding officer may promulgate a list of active parties and identify types of documents that need not be served on parties omitted from that list. Omission from that list, however, shall not otherwise affect a party's standing.

(3) To avoid unnecessary duplication, the presiding officer may require parties with similar interests to consolidate their presentations.

(1) Any person may ask the presiding officer for permission to intervene. Permission will be granted if the intervention is likely to contribute to the development of a complete record or is otherwise fair and in the public interest.

(2) Permission to intervene after a hearing has commenced may be sought and granted at any time, unless the presiding officer determines that granting such permission would be unfairly prejudicial to other parties. A party intervening after the start of the hearing shall be bound by the record as developed to that point and by such conditions of intervention as the presiding officer may impose.