ITU-T Rec. K.27 (1991) – BONDING CONFIGURATIONS AND EARTHING INSIDE A TELECOMMUNICATION BUILDING
FOREWORD
1 Introduction
2 Scope
3 Definitions
    3.1 IEC definitions
        3.1.1 earth
        3.1.2 earth electrode
        3.1.3 earthing network
        3.1.4 main earthing terminal
        3.1.5 earthing conductor
        3.1.6 equipotential bonding
        3.1.7 equipotential bonding conductor
        3.1.8 neutral conductor (N)
        3.1.9 protective conductor (PE)
        3.1.10 PEN conductor
    3.2 Definitions for telecommunication earthing installations
        3.2.1 bonding network (BN)
        3.2.2 common bonding network (CBN)
        3.2.3 mesh-BN (MBN)
        3.2.4 isolated bonding network (IBN)
        3.2.5 single point connection (SPC)
        3.2.6 SPC window (SPCW)
        3.2.7 mesh-IBN
        3.2.8 star IBN
        3.2.9 system block
        3.2.10 isolated d.c. return (d.c.-I)
        3.2.11 common d.c. return (d.c.-C)
4 Principles of bonding and earthing
    4.1 Summary of theory
    4.2 Implementation principles
        4.2.1 Implementation principles for the CBN
        4.2.2 Implementation principles for a mesh-BN
        4.2.3 Implementation principles for an IBN
    4.3 Protection against electric shock
    4.4 Protection against lightning
    4.5 Functional earthing
5 Power distribution
    5.1 A.c. power distribution
    5.2 D.c. power distribution
6 Comparison between IBN and mesh-BN installations
7 Maintenance of bonding networks
8 Examples of connecting equipment configurations to the CBN
ANNEX A – Brief theory of bonding and earthing networks
A.1 Overview
ANNEX B – Examples of bonding configurations
B.1 Mesh-BN
B.2 Mesh-IBN with a bonding mat configuration
B.3 Star or sparse-mesh IBN with isolation of d.c. power return
References