scope:

Experience in the operation of telecommunication centres shows that the use of a bonding and earthing network that is coordinated with equipment capability and with electrical protection devices, has the following attributes:

- promotes personnel safety and reduces fire hazards;

- enables signalling with earth return;

- minimizes service interruptions and equipment damage;

- minimizes radiated and conducted electromagnetic emissions;

- reduces radiated and conducted electromagnetic susceptibility;

- improves system tolerance to discharge of electrostatic energy, and lightning interference.

Within this framework, this Recommendation:

a) is a guide to bonding and earthing of telecommunication equipment in telephone exchanges and similar telecommunication switching centres;

b) is intended to comply with safety requirements imposed by IEC [2] or national standardizing bodies on a.c. power installations;

c) can be used for installation of new telecommunication centres, and, if possible, for expansion and replacement of systems in existing centres;

d) treats coordination with external lightning protection, but does not provide details of protective measures specific to telecommunication buildings;

e) addresses the shielding contribution of the effective elements of the building;

f) addresses shielding provided by cabinets, cable trays and cable shields;

g) is intended to encourage EMC planning, which should include bonding and earthing arrangements that accommodate installation tests and routine diagnostics;

h) does not include:

- required values of surge current immunity and insulation withstand voltages;

- limits of radiated and conducted electromagnetic emission or immunity;

- techniques for verifying and maintaining bonding and earthing networks.