scope:

This instruction applies to all persons engaged in the maintenance of telecoms copper cables for Network Rail.

The VL & VT tests are designed to produce data on which to base an assessment of the protection afforded by the immunisation system.

Purpose

This telecoms maintenance instruction defines the maintenance requirements for copper cables in use on Network Rail infrastructure.

The purpose of undertaking cable noise immunity tests, in AC electrified areas, is to ensure that voltages induced into telecommunications cables are within safe limits and that noise levels are not causing interference to the operation of telecom systems and services.