Siemens SCALANCE M804PB Operating Instructions Manual page 32

Installation
4.3 Installing on the DIN rail
Connect the terminal with as short a cable as possible ≤ 150 mm and a large cross-sectional
area of 1.5 mm² to the functional ground of the system, see section "Terminals (Page 20)"
and section "Grounding (Page 42).
7. Also connect the DIN rails of a system with functional ground.
Dismantling
1. Disconnect all connected cables.
2. Using a screwdriver, pull down the catch on the rear of the device.
3. Pull lower part of the device away from the DIN rail.
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Operating Instructions, 07/2018, C79000-G8976-C496-01
SCALANCE M804PB