Grounding and lightning protection
Overview
The primary goal of an earthing system is to assure personnel safety and protection of
installations against damage. Two important phenomena are lightning and power system
faults. These can cause circulation of large currents, which may create hazardous voltages
in the installation.
•For lightning, the task of the earthing system is to provide a path to the soil for
dangerous currents, while maintaining potential differences between any two points of
an installation as low as possible.
•For power system faults, it provides a safe path for fault currents, while also
maintaining potential differences between any two points of an installation as low as
possible.
Codes and standards
Regulatory grounding codes and standards may differ from region to region and country
to country. The grounding/bonding of the installation site and Alcatel-Lucent 9764 Metro
Cell Outdoor must follow national and/or local regulatory codes and standards in
countries and localities where these exist.
Examples of these regulatory codes and standards are:
•National Electric Code (NFPA 70), USA
•Canadian Electrical Code, Part I (CSA C22.1)
•BS 7671 (UK IEE Wiring Regulations, BS 7671
•VDE 0100, Germany
•International Electrotechnical Commission's international standard, 60364
Grounding requirements
The Alcatel-Lucent 9764 Metro Cell Outdoor can be susceptible to lightning surges due to
its association with elevated installation locations. It is therefore imperative that the
equipment and installation site be properly grounded to a reliable and effective grounding
electrode system such that a low impedance path to earth is provided.
For Alcatel-Lucent 9764 Metro Cell Outdoor installations the following grounding system
types are supported:
•TN
In a TN earthing system, one of the points in the generator or transformer is connected
with earth, usually the star point in a three-phase system. The body of the electrical
device is connected with earth via this earth connection at the transformer.
•TT
Grounding and lightning protection requirements Grounding and lightning protection
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4-2 Alcatel-Lucent – Proprietary
Use pursuant to applicable agreements
Alcatel-Lucent 9764 MCO
3MN-01702-0001-RJZZA
Issue 5 June 2014