To increase safety in the event of access to a total system 1; 32 in particular a medical system, with a field 3.1; 33.1 of high magnetic field intensity, a subsystem 5-12; 22-26, in particular with a light barrier 6 and/or a metal detector 5 and/or a door contact 25, is provided as the means for detecting access. According to one embodiment of the invention, the field line pattern and/or the intensity of the magnetic field is graphically represented by means of a luminescent display field 24 located on the floor, in particular made of photodiodes 31.