This chapter aims to report some plastic optical fiber applications that have been used by the Photonics and Instrumentation Laboratory in specific areas and have not been published so far as conventional papers. They are specific applications designed to solve specific problems in the oil and gas industries and electric power sector. A switch or disconnector is power substation maneuvering equipment, a component of the electric power system that has the function of establishing the electric connection between generators, transformers, consumers, and transmission lines and disconnecting them, according to the requirements of the service. The safety sensor consists of an Arduino UNO microcontroller with an SD memory card module, a real-time clock module and a Bluetooth module. The microprocessor controls the light-emitting diode (LED) that injects light into a plastic optical fiber. The light emitted by the LED is guided to the sensor where it is reflected back by the micro-mirror.