This report contains the influencing factors in high voltage overhead power lines and how these factors are controlled and calculated. A program has been produced so that a projector easily can insert the overhead line supports’ and lines’ parameters in the program. The program calculates and controls the distances required within the support and if the construction is requisite for the chosen system voltage and support site. The program controls for instance the distance between the phases, between phase line and top line, guy wires, cross arm and poles. The program creates a output file which is a summary of the support and warns if the required distances within the support is not fulfilled. The supports that are most exposed to forces are angular supports (where the overhead power line changes direction) and end supports (where the overhead line ends).