N.C. Gen. Stat. § 131A-18
The Commission is hereby authorized to provide for the issuance of refunding bonds or notes for the purpose of refunding any bonds or notes then outstanding which shall have been issued under the provisions of this Article, including the payment of any redemption premium thereon and any interest accrued or to accrue to the date of redemption of such bonds or notes and, if deemed advisable by the Commission, for any corporate purpose of the Commission, including, without limitation:
The issuance of such bonds or notes, the maturities and other details thereof, the rights of the holders thereof, and the rights, duties and obligations of the Commission in respect of the same shall be governed by the provisions of this Article which relate to the issuance of bonds or notes, insofar as such provisions may be appropriate therefor.
Refunding bonds or notes may be sold or exchanged for outstanding bonds or notes issued under this Article and, if sold, the proceeds thereof may be applied, in addition to any other authorized purposes, to the purchase, redemption or payment of such refunding bonds or notes, with any other available funds, to the payment of the principal, accrued interest and any redemption premium on the bonds or notes being refunded, and, if so provided or permitted in the resolution authorizing the issuance of, or in the trust agreement securing, such bonds or notes, to the payment of any interest on such refunding bonds or notes and any expenses in connection with such refunding, such proceeds may be invested in direct obligations of, or obligations the principal of and the interest on which are unconditionally guaranteed by, the United States of America which shall mature or which shall be subject to redemption by the holders thereof, at the option of such holders, not later than the respective dates when the proceeds, together with the interest accruing thereon, will be required for the purposes intended.
N.C. Gen. Stat. § 131A-18