The authors expose some useful efficient techniques for Boundary Integral Equations in application package development. Problems particular to BIE techniques are solved : -Physical singularity in geometry corners where uniqueness of normal flux density cannot be obtained. A double flux formulation gives the exact values of flux. -The need for good accuracy on solid angle value at each point of the mesh has been proved. An original technique allows automatic computation of this value. Finally the authors show how to use the features of the BIE method (computation of both flux density and potential) to plot at a minimum computing cost the equipotential lines in a system.