Abstract: The device for measuring the energy of an electric arc consists of a supp (1) for at least one optical fiber disposed on the head of an electrode (2) of the arc, the support being made of a plastic material of suitable dielectric strength, one or several optical fibers (10) constrained on the support and one end or ends whereof arrive near the tip of the electrode, an optical connector (15, 16) receiving on the one hand the other end of said fibers(s) and on the other hand the end of an optical fiber cable (17) for connecting with a photoelectric cell (18), a photoelectric cell (18) disposed at some distance from the electrode and electronic means (20) connected to the cell (18) and used to record and display the energy given off by the arc.

Abstract: A method of manufacturing an optical fiber cable of the type which compri at least one cellular cylindrical structure of plastic material having a plurality of longitudinal bores housing individual optical fibers and filled with a viscous substance. The viscous substance is injected around the fibers under pressure as they pass along tubes which each have a gap of some length so that said viscous substance can enter the tubes. The optical fibers coated with viscous substance are made to protrude beyond the ends of said tubes. A thermoplastic material is simultaneously extruded through an annular orifice and around the optical fibers under a pressure which is sufficient to completely surround said coated optical fibers. The cylindrical structure thus obtained is rapidly cooled.