The Santee Cooper (Moncks, South Carolina, U.S.) system is made up of approximately 4500 miles (7242 km) of transmission lines and 2500 miles (4023 km) of distribution lines. The Santee Cooper transmission operations department is responsible for the inspection, maintenance and operation of the transmission system, which consists mainly of 69-kV, 115-kV and 230-kV lines. The department also maintains the rights-of-way and investigates danger trees.

In the latter part of 2002, the engineering and technical support group began tracking causes for wood pole changeouts. In its geographic information system, Santee Cooper has the transmission system entered graphically by global positioning system coordinates and maintains a database tied to the graphics, collecting useful information including pole date, pole size, pole class, structure type, structure drawing number, shieldwire and conductor type, shieldwire and conductor tension, line name, line ID, and plan and profile drawing number.

Santee Cooper has tracked the age of the poles when being changed out and performed predictive replacement modeling, as provided by KEMA, to determine present and future change-out rates. Santee Cooper's change-out rates were 0.30% in 2003, 0.33% in 2004 and 0.39% in 2005. It is predicted that by 2030, the change-out rate will be around 1.2%. The utility will continue to track this information to see how well these predicitions hold. Santee Cooper's reliability remains consistently good, so the company will not radically increase its investment in change-outs. However, if change-out rates continue to rise, Santee Cooper will increase its investment in the maintenance program.

For more information, contact dldodson@santeecooper.com.