Section 12. Local bonds.

Counties, school districts, municipalities, special districts and local governmental bodies with taxing powers may issue bonds, certificates of indebtedness or any form of tax anticipation certificates, payable from ad valorem taxation and maturing more than twelve months after issuance only:
(a) to finance or refinance capital projects authorized by law and only when approved by vote of the electors who are owners of freeholds therein not wholly exempt from taxation; or
(b) to refund outstanding bonds and interest and redemption premium thereon at a lower net average interest cost rate.