This paper presents a novel experimental cell designed by EDF-R&D to investigate thermo-aeraulic phenomena in rooms housing thermosensitive electrical equipment, particularly relevant for nuclear power plants. The facility is a full-scale test room with concrete walls, covering an area of 40 m2 and is equipped with mechanical ventilation, including a supply air inlet and an exhaust outlet. Multiple full-scale electrical cabinets are placed inside the room to simulate the heat dissipation of electrical equipment. The test cell is highly instrumented to allow experiments to be carried out under controlled conditions to validate numerical models, including both nodal and 3D representations. Temperature measurements in the concrete walls and air are conducted using Raman scattering optical fibers, providing detailed 3D temperature field reconstructions. This paper introduces the first study-case spanning four days, during which the experimental setup reaches a steady state. This paper introduces the first study-case spanning four days, during which the experimental setup reaches a steady state. In this preliminary experiment, ventilation is deliberately excluded to emphasize the exploration of natural convection. The recorded data allows the analysis of the thermo-aeraulic behavior of an electrical cabinet room and highlight the coherence of the multiple measurements, validating the facility's ability to provide reliable reference data for studies in rooms containing thermosensitive electrical equipment.