SAGSEC is a powerful and easy to use Microsoft Windows program for the exact nonlinear 3-dimensional static analysis of a multi-span tension section (single ground wire or conductor between two dead-end attachment points). Structural supports for all clamps and insulators can either be fixed or flexible (with specified transverse and longitudinal stiffness). The swings of the insulators as well as their weights and wind areas are accounted for in 3-dimensions. Marker balls can be installed at arbitrary locations along the spans. SAGSEC is commonly used to determine the sags, tensions and support reactions of a tension section when the simplifying concept of “ruling span” is not appropriate. It can calculate the section static equilibrium configuration for arbitrary combinations of: 1) sagging conditions, 2) wind velocity and direction, 3) balanced or unbalanced ice, 4) temperature, 5) broken conductors or insulators, 6) slack redistribution through offsets or other means and 7) support relocations with a fixed length of cable between the dead ends.