As the properties of high-T/sub c/ superconducting tapes improve, practical design considerations require more detailed analysis. Here we report investigations of the stability of high-T/sub c/ superconducting tapes. As a result of the broad range of temperature during a transition and the strong temperature dependence and anisotropy of the material properties, the finite element method (FEM) is used to solve the three-dimensional heat conduction equation. The heat source is determined using the operating current, the resistivity of the materials and the critical current density of Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ (BSCCO). The minimum quench energy for several sources is determined for both infinitely long and planar uniform sources in the BSCCO and the two cases are compared.