Within this paper, we will describe a grid concept to realize a universal remote lab infrastructure as well as different operation modes based on this concept. This new infrastructure consists of three parts: an internal serial remote lab bus, a bus protection unit to interface the remote lab bus and to protect it from misuse and damage as well as a protection unit, which protects the physical systems (the electro-mechanical models in our remote lab) against deliberate damage or accidentally wrong control commands and which offers different access and control mechanisms. The interconnection between the Web-control units and the selected physical system during a remote lab work session (experiment) as well as the user management is done by the lab server, which also handles the webcams. The implemented remote lab infrastructure is based on the iLab architecture of the MIT, which allows to interconnect remote labs and to exchange remote lab experiments among different universities worldwide.