Cable Selection

Selection starts from the duty, not from a catalogue page. Five answers decide almost every construction: the system voltage and the earthing arrangement, the continuous and short-circuit current, the installation method, the environment the cable will sit in, and the standard the project follows. Once those are fixed, conductor size and material, insulation type, screen and sheath mostly follow.

The reverse order is where projects go wrong. Choosing a cable first and then checking whether it suits the route, the ambient temperature or the fault level usually ends in a larger, more expensive cable than the duty needed — or in one that cannot be corrected at all because the tray width or the bending space was already set.