In the last decade, Reconfigurable Manufacturing Systems (RMS) have been proposed to deal with mass-customization problems and volatile markets. Applied to the field of assembly, this concept gives rise to Reconfigurable Assembly Systems (RAS). The latter are composed of different basic units (e.g., conveyor units, robotized units) linked together. Issues regarding the physical design, scheduling, and control of RAS have been studied intensively but very few studies have addressed safety problems. However, this issue is of primary concern for RAS containing robotized units with frequent interventions of human operators. Indeed, traditional safety approaches fail to take into account the versatility of RAS. In this context, the paper proposes a new way of dealing with safety in RAS with the concept of “safety bubble”. The latter aims to ensure operator safety by sharing safety data between units. An implementation methodology of this safety bubble is presented and on-going developments “off-line” on a multi-agent platform and “on-line” on a real demonstrator are described.