A commissioner or employee of the Commission who receives an ex parte communication that concerns a case where a determination or decision is required by law to be made only after a public hearing for interested parties shall make the ex parte communication public and part of the record of the proceeding. A commissioner or employee of the Commission who receives an ex parte communication that concerns the merits of a case where the commissioner’s or employee’s determination or decision is required by law to be made only after a public hearing for interested parties shall: note the substance of an oral ex parte communication for the record; and place the substance of a written ex parte communication on the record.