(1) Any person interested in and directly affected by the subject matter of any hearing or investigation pending before the commission may petition to become a party thereto. Intervenors shall have the right to call and examine witnesses, cross-examine opposing witnesses, and be heard on all matters relative to the issues involved. The petition to intervene shall be filed with the commission and shall contain the docket number and title of the proceeding, and all such contents required for pleadings set forth in these rules. The petition shall also indicate whether general or special intervention is sought.
(2) In the discretion of the commission or hearing examiner persons desiring to testify at a commission hearing may be allowed to do so without filing a petition to intervene. Such persons may also be allowed to cross-examine witnesses.