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Cisco MGX 8950 Hardware Installation Guide
Release 3, Part Number 78-14147-02 Rev. A0, November 2002
Appendix C Earthing and Bonding Recommendations
EC [3] Definitions
K.27 Definitions
The following definitions apply to terminology found in K.27:
Bonding network (BN) A set of interconnected conductive structures that provide an
electromagnetic shield for electronic systems and personnel at
frequencies from DC to low RF. The term “electromagnetic
shield” denotes any structure used to divert, block, or impede
electromagnetic energy. In general, a BN need not be connected
to earth, but all BNs in this recommendation have an earth
connection.
Common bonding network (CBN) The CBN is the primary way to create effective bonding and
earthing inside a telecommunication building. It is the set of
metallic components that are intentionally or unintentionally
interconnected to form the principal BN in a building. These
components include:
• Structural steel or reinforcing rods
• Metallic plumbing
• AC power conduit
• PE conductors
• Cable racks
• Bonding conductors
The CBN always has a mesh topology and is connected to the
earthing network.
Mesh-BN (MBN) A bonding network in which all associated equipment frames,
racks, cabinets, and the DC power return conductor are bonded
together and also bonded at multiple points to the CBN.
Consequently, the mesh-BN augments the CBN.
Isolated bonding network (IBN) A bonding network that has a single point of connection (SPC)
to either the common bonding network or another isolated
bonding network. All IBNs in this document will have a
connection to earth via the SPC.
Single point connection (SPC) The unique location in an IBN where a connection is made to the
CBN. In reality, the SPC is not a mere “point” but has sufficient
size to accommodate the connection of multiple conductors.
Usually, the SPC is a copper bus-bar. If cable shields or coaxial
outer conductors are to be connected to the SPC, the SPC could
be a frame with a grid or sheet metal structure.