Rec. ITU-T K.66 (11/2019) Protection of customer premises from overvoltages
Summary
FOREWORD
Table of Contents
Introduction
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Responsibility
     5.1 Building owner
     5.2 Manufacturer
     5.3 Network operator
     5.4 Customer
6 Risk management
     6.1 Sources of damage
     6.2 Risk assessment
     6.3 Risk reduction
7 Objectives for bonding configurations and earthing
8 Protection requirements
     8.1 Equipotential bonding
     8.2 a.c. power distribution and SPDs
     8.3 Telecommunication lines and SPDs
     8.4 Selection of SPDs for installation at the point of entry
          8.4.1 a.c. power distribution
          8.4.2 Telecommunication lines
9 Installation of SPDs (primary protectors)
     9.1 Installation methods for SPDs (primary protection) for different power distribution systems
     9.2 Examples of installation methods to achieve the requirements of short bond wires
          9.2.1 Co-location of services near the MET
          9.2.2 Combined utility enclosures
          9.2.3 Common bonding network
          9.2.4 Ring earth electrode
          9.2.5 Ring conductor
     9.3 Location of the telecommunication SPD
     9.4 Safety issues
10 Multiservice surge protective devices
     10.1 Single MSPD
     10.2 Multiple MSPDs
11 Implementation
12 Large installations
Annex A  Installation methods for different power systems
     A.1 Installation method for TN-S power distribution systems
          A.1.1 Installation method for a TN-S power distribution system with separate neutral and protective conductors (MET installed outside the main a.c. service cabinet)
          A.1.2 Installation method for a TN-S power distribution system with separate neutral and protective conductors (MET installed inside the main a.c. service cabinet)
          A.1.3 Installation method for a TN-S power distribution system with earthed line conductor (MET installed outside the main a.c. service cabinet)
          A.1.4 Installation method for a TN-S power distribution system with earthed line conductor (MET installed inside the main a.c. service cabinet)
     A.2 Installation method for TN-C-S power distribution systems
          A.2.1 Installation method for a TN-C-S power distribution system, with earth neutral link, (MET installed outside the main a.c. service cabinet)
          A.2.2 Installation method for a TN-C-S power distribution system, with earth neutral link, (MET installed inside the main a.c. service cabinet)
          A.2.3 Installation method for a TN-C-S power distribution system, without earth neutral link, (MET installed outside the a.c. service cabinet)
          A.2.4 Installation method for a TN-C-S power distribution system, without earth neutral link, (MET installed inside the a.c. service cabinet)
     A.3 Installation method for TN-C power distribution systems
          A.3.1 Installation method for a three-phase 4-wire TN-C power distribution system, (MET installed outside the main a.c. service cabinet)
          A.3.2 Installation method for a three-phase 4-wire TN-C power distribution system, (MET installed inside the main a.c. service cabinet)
          A.3.3 Installation method for a single-phase three-wire TN-C power distribution system, (MET installed outside the main a.c. service cabinet)
          A.3.4 Installation method for a single-phase three-wire TN-C power distribution system, (MET installed inside the main a.c. service cabinet)
     A.4 Installation method for TT power distribution systems
          A.4.1 Installation method for a three-line and neutral TT power distribution system, (MET outside the main a.c. service cabinet)
          A.4.2 Installation method for a three-line and neutral TT power distribution system, (MET inside the main a.c. service cabinet)
          A.4.3 Installation method for a single-phase 3-wire TT power distribution system, (MET outside the main a.c. service cabinet)
          A.4.4 Installation method for a single-phase three-wire TT power distribution system, (MET inside the main a.c. service cabinet)
          A.4.5 Installation method for a three-line (without neutral) TT power distribution system, (MET outside the main a.c. service cabinet)
          A.4.6 Installation method for a three-line (without neutral) TT power distribution system, (MET inside the main a.c. service cabinet)
     A.5 Installation method for IT power distribution systems
          A.5.1 Installation method for a three-line (and neutral) IT power distribution system, (MET outside the main a.c. service cabinet)
          A.5.2 Installation method for a three-line (and neutral) IT power distribution system, (MET inside the main a.c. service cabinet)
          A.5.3 Installation method for a three-line (without neutral) IT power distribution system, (MET outside the main a.c. service cabinet)
          A.5.4 Installation method for a three-line (without neutral) IT power distribution system, (MET inside the main a.c. service cabinet)
Annex B  Solutions for earthing and bonding problems
     B.1 Methods to improve earthing and bonding
     B.2 Methods of providing additional protection external to the equipment
     B.3 Special resistibility and safety requirements
Appendix I  Earthing and bonding scenarios
Appendix II  Examples of mitigation measures for different power installations
     II.1 TN-C and TN-C-S types
     II.2 TT and IT types
Appendix III  Surge current paths and resulting potential differences