DIN rails are the metal rails inside an electrical enclosure that are used to mount circuit breakers and other types of electrical equipment. Although DIN rails have a relatively simple design, they're extremely important for the installation, maintenance and operation of electrical. A DIN rail is a standard type metal rail that is utilized for mounting circuit breakers and industrial control equipment in equipment racks. In addition, it acts as a mechanical support structure for different types of small electrical parts. Originally conceived in Germany the name DIN-Rail was based on the DIN (Deutsche Industrie Norm) which translates to German Industrial Standard which defined the dimensions and. Circuit breakers have markings stamped on the side of them and are usually located inside the panel cover door. There is a label that will tell you what type of breaker is needed for installation in that particular panel.