Siemens SIMATIC ET 200SP System Manual page 300

Distributed I/O system
System Manual, 09/2019, A5E03576849-AJ
Symbol Meaning
For Zone 2 potentially explosive atmospheres, be aware that the device may only
be used when it is installed in an enclosure with a degree of protection ≥ IP54.
For Zone 22 potentially explosive atmospheres, be aware that the device may
only be used when it is installed in an enclosure with a degree of protection ≥
IP6x.
D.2 Safety-related symbols for devices with Ex protection
Safety-relevant symbols
299