Santee Cooper’s board of directors today approved the sale of nearly $507 million bonds in a move that wraps up a record $1.8 billion financing deal that began last month.

The tax-exempt debt was issued in two series that have exceptionally long-term maturities of 35 and 40 years.

The state-owned power and water utility is paying 5.34 percent interest on the bonds.

The board of Moncks Corner-based Santee Cooper on Aug. 19 unanimously authorized a $1.34 billion debt sale, a record for state agency in South Carolina.

“This bond sale finishes what we started back in August, which was to sell around $1.75 billion in bonds with an emphasis on longer-term maturities. The long-term market weakened just prior to our August sale, and so we chose to hold off on our 35- and 40-year bonds,” said Jeff Armfield, senior vice president and chief financial officer. “We’ve been watching for better market conditions, and I’m pleased we could respond so quickly and achieve our financing targets.”

Most of the proceeds from will be used to refinance old debt. The rest will help pay for construction projects, including the expansion of the V.C. Summer Nuclear Station north of Columbia.

Today’s debt issue drew credit ratings of AA- from Fitch Ratings and Standard & Poor’s, and an A1 from Moody’s Investment Service, the utility said. Bank of America Merrill Lynch handled the transaction.