In earlier experimental investigations into the functional simulation of insulation loss in branch circuit conductors, the authors normalized the arcing-fault simulation to be used in laboratory tests. This conventional simulation allows one to characterize this intrinsically random phenomenon by means of a probabilistic approach, in order to define in statistical terms the expected short circuit value. The authors examine more closely the arcing fault in the design of sub-distribution branch circuits as weak points of the installation. Straightforward criteria are proposed, whether in the structure of the system or in the coordination of protection, which afford a more rational control on arcing fault. >