N.C. Gen. Stat. § 123-11

At the time and place appointed, and before the commencement of the trial, the presiding officer of the Senate shall administer to each member of the court then present, and to other members as they appear, an oath or affirmation truly and impartially to try and determine the charge in question, under the Constitution and laws, according to the evidence. No member of the court shall sit or give his vote upon the trial until he shall have taken such oath or affirmation.