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: Device for sealing a container and process for detecting an attempted break-in with the aid device. In per se known manner, part of the fibres at one end of an optical fibre cable is masked and the other end of the cable is observed on illuminating the first end. According to the invention, the two cable ends are held in a seal, while masking is obtained either with the aid of a masking disk, or with the aid of a high-energy beam, which destroys the end of certain fibres. The second end of the cable is observed either with the aid of a camera, or with the aid of a sighting camera making it possible to mark the coordinates of the unilluminated fibres.