Preventative maintenance strategies are growing in importance in Industry 4.0 thanksto the new possibilities offered by the developing technologies. The possibility of remotelymonitoring the system and take actions based on real time data before seriousfaults occur is also possible by employing wireless sensors in the so called WirelessSensors Networks (WSNs).In the presented work, the state of the art of preventative maintenance in Industry 4.0is discussed. After defining desirable characteristics, sensing technologies for vibration,temperature, magnetic field, audio and humidity are analysed and the suitability of eachof them for industrial environments is discussed. Different communication protocolsfor wireless sensor nodes are described and compared in order to perform the optimalchoice according to the requirements and constraints of the application.