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Cisco MGX 8800/8900 Series Hardware Installation Guide
Releases 2 - 5.2, Part Number OL-4545-01, Rev. H0, May 2006
APPENDIX
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Earthing and Bonding Recommendations

Note This appendix applies to the Cisco MGX switches and gateways described in this guide: MGX 8850
(PXM45/PXM1E), MGX 8850/B, MGX 8950, MGX 8830 and MGX 8830/B multiservice switches and
the MGX 8880 Media Gateway.
This appendix discusses the techniques and policies that Cisco pra ctices with regard to DC power,
earthing, and bonding of Cisco equipment. It also explains why these techniques are the best practice.
More specifically, this appendix describes the techniques for DC power and earth bonding for
Cisco MGX switches.
The appendix also discusses the principles of mesh bonding and explains the earth return systems that
are used in the Cisco MGX switch. It identifies the earthing points, shows how they are to be earthed,
and how the DC power connections are to be connected to the equipment.
The earthing and powering techniques described in this appendix are extracts from Cisco intern al
documentation, engineering documentation, and the following standards documentation:
•ITU-T K.27, Bonding configurations and earthing inside a telecommunications building
•GR-1089-CORE, Electromagnetic compatibility and elec trical safety—generic criteria for network
telecommunications equipment

Scope

The bonding and earthing principles adopted by Cisco are as follows:
•Promote personal safety and reduce fire hazards
•Enable telecomm signaling with earth return
•Minimize equipment damage and service interruption
•Minimize radiated and conducted electromagnetic emissions and susceptibility
•Maximize tolerance to discharge of electrostatic energy and lightning interference
This appendix supports the principles listed above by providing information that complies with relevant
safety standards on the following topics:
•Bonding and earthing of the Cisco WAN equipment at the telco sites
•Shielding provided by cabinets, cable trays, and cable shields
•Techniques for verifying and maintaining bonding and earthing networks