Siemens S7-400 Installation Manual page 264

Assembling and Installing Systems
Ensure the following for frame and wall mounting:
• Use special contact washers with painted and anodized metal parts, or remove
the insulating protective layers.
• Provide large-area, low-impedance metal-to-metal connections when securing
the shield/protective ground bar.
• Cover the AC supply conductors in a shockproof arrangement.
Figure A-3 shows an example of wall mounting for EMC
Figure A-3
A-12
Wall Mounting an S7-400 for EMC
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04