Pub. Util. Code, § 29219

Refunding bonds may be issued in a principal amount sufficient to provide funds for (a) the payment of the principal of and interest on the bonds, notes or other evidences of indebtedness to be refunded; (b) all expenses incidental to the calling, retirement or payment of the outstanding bonds, notes or other evidences of indebtedness and the issuance of refunding bonds including the difference in amount between the par value of the refunding bonds and any amount less than par; (c) any amount necessary to be made available for the payment of interest upon the refunding bonds from the date of their delivery to the date of maturity or payment of the bonds, notes or other evidences of indebtedness to be refunded out of the proceeds of sale or the date upon which the bonds, notes or evidences of indebtedness to be refunded will be paid pursuant to call and redemption thereof or pursuant to any agreement with the holders thereof for the refunding or exchanging of such bonds, notes or other evidences of indebtedness; and (d) the premium if any necessary to be paid in order to call and retire the outstanding bonds, notes or other evidences of indebtedness to be refunded. Refunding bonds may be exchanged at not less than their par value and accrued interest for outstanding bonds, notes or other evidences of indebtedness to be refunded thereby.