Siemens SIMATIC NET PROFIBUS Owner's Manual page 281

Cabinet Lighting
Use bulbs for the cabinet lighting, for example LINESTRAR lamps. Avoid the use
of fluorescent lamps since they cause interference. If you need to use fluorescent
lamps, take the measures shown in Figure C-5.
Figure C-5
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Wire-mesh screen over the lamp
Shielded cable
Metal-encased switch
Power supply filter or shielded
power cable
Measures for Interference Suppression of Fluorescent Lamps in a Cabinet
Installing LAN Cables
C-19