(a) How requested. Intervention will normally be granted only upon petition. In exceptional circumstances, where the issues would not be broadened or the proceeding delayed, an officer may, at his or her discretion, allow intervention upon motion made orally at the hearing.

(b) Content generally. A petition for leave to intervene must set forth the grounds for the proposed intervention, the position and interest of the petitioner in the proceeding, and whether petitioner's position is in support of or in opposition to the relief sought. If the proceeding is by formal complaint and affirmative relief is sought by petitioner, the petition should conform to the requirements for a formal complaint.

(c) When filed. A petition for leave to intervene in any proceeding should be filed prior to or at the time the proceeding is called for hearing, but not after, except for good cause shown.

(d) Broadening issues; filing. If the petition seeks a broadening of the issues and shows that they would not thereby be unduly broadened, and in respect thereof seeks affirmative relief, the petition should be filed in time to permit service upon and answer by the parties in advance of the hearing.

(e) Copies; service; replies. When a petition for leave to intervene is tendered at the hearing, sufficient copies of the petition must be provided for distribution to the parties represented at the hearing. When a petition for leave to intervene is not tendered at the hearing, the petition should be submitted to the Board together with a certificate that service has been made by petitioner. Any reply in opposition to a petition for leave to intervene not tendered at the hearing must be filed within 20 days after service of the petition to intervene. At the discretion of the Board, leave to intervene may be granted or denied before the expiration of the time allowed for replies.

(f) Disposition. Leave to intervene will be granted only when the petitioner addresses issues reasonably pertinent to the issues already presented and which do not unduly broaden them. If leave is granted the petitioner becomes an intervener and a party to the proceeding.