(b) The following prohibition shall apply to adjudicatory proceedings, including public hearings pursuant to Part 580 and Subparts 581-3 and 581-4 of this Title, or variance hearings pursuant to Part 576 of this Title.

1. (1) No party or representative of a party shall communicate in any form with the agency or any member regarding any matter subject to an adjudicatory proceeding before the agency without serving copies of the communication on all other parties to the proceeding.

2. (2) Prior to or during an adjudicatory proceeding, no agency member or employee responsible for rendering a decision or making findings of fact and conclusions of law shall communicate in connection with any issue of fact, or issue of law, with any person, party or his representative, except upon notice and opportunity for all parties to participate; provided, however, that any agency member or employee:

   1. (i) may communicate with other members of the agency; and
   2. (ii) may have the aid and advice of agency staff which have not been engaged in the investigation or prosecuting functions in connection with the matter or proceeding or factually related matter or proceeding.

(c) Prohibition