Siemens SIMATIC ET 200AL System Manual page 36

Mounting
To connect modules of the ET 200AL distributed I/O system to functional earth, proceed as
follows:
1. Drill two fastening holes.
2. Strip the grounding cable.
3. Fasten the cable lug to the grounding cable.
4. Screw the module and the cable lug with the M4 fastening screws using a torque of
1.2 Nm.
The figure below shows how to connect functional earth using the example of the
IM 157-1 PN interface module.
Figure 5-6
Note
Earthing with non-conductive mounting substrate
Make sure there is a low-impedance connection between the module and the functional
earth.
Reference
You will find more information on installing the modules in the section Mounting modules
(Page 21).
Distributed I/O system
System Manual, 08/2019, A5E31861578-AG
Connecting the functional earth
5.4 Connecting ET 200AL to functional earth
Connecting
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