scope:

INTRODUCTION

This module applies to the design of Transmission Systems (including Cables, Terminations and Cable Routes).

Transmission systems (including cables) are provided as a means of interconnecting systems, sub-systems or items of equipment. Additionally, cables (commonly, but not universally single core) are provided as part of the internal circuitry of individual items of equipment.

Cables fall into four broad areas of application:

a) internal wires within an installation or sub-system (predominantly single core);

b) main cables providing external transmission between installations or subsystems including power distribution, direct-wired, remote control and datalink systems;

c) tail cables providing connection from lineside equipment housings to trackside or on-track equipment (sometimes via disconnection boxes), including track circuit connections and lineside operational telephone cables;

d) bonding cables (usually single core) provided for track circuit, earth and equipotential bonding.

Terminations are provided as a means of interfacing between differing types and/or sizes of cable and also in order to provide circuit disconnection and/or test facilities.

Cable routes are provided as a means of constraining cables and also protecting them from their environment.

This Part may not be applicable to the internal wiring of sealed manufactured units. In this case alternative arrangements should be agreed as part of the approval process.

Where it entirely addresses the situation under consideration, the use of this Company Standard, is an alternative to an approved form of risk-based assessment. However, where the particular application or intended environment for the system introduces additional risks, these should be subject to separate assessment.

The Design Principles in Section 2 give the minimum requirements, even when the risk-based approach is used. These principles are mandated in NR/L2/SIG/11201.