scope:

INTRODUCTION

This module applies to the design of electrical circuits associated with:

a) electro-mechanical signalling systems;

b) electro-pneumatic signalling systems;

c) relay based signalling systems; and

d) electronic signalling systems.

It applies to both internal and external circuits, commencing on the load side of the final busbar.

It does not apply to wiring associated with the power supply side of the final busbar, which is covered in NR/L2/SIG/30050, nor to circuits associated with signaller's voice communication systems, which are covered in NR/L2/TEL/30002, NR/L2/TEL/30031, NR/L2/TEL/30032 & NR/L2/TEL/30143.

For the presentation and use of circuit diagrams within the design process see NR/L2/SIG/11201, Module A2 & A15. Relay and circuit nomenclature, as well as symbols, are defined in NR/L2/SIG/11201, Module A19.

Where it entirely addresses the situation under consideration, the use of this Standard is an alternative to an approved 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 that need to be addressed, even when a risk-based approach is used. These principles are mandated in NR/L2/SIG/11201.

The following guidelines and specifications should satisfy the principles encompassed within the standard:

a) guidelines on fusing and looping in NR/L2/SIG/11201, Module B4;

b) guidelines on the electromagnetic compatibility of electronic equipment in NR/L2/SIG/11201, Module B5;

c) guidelines on protection of conductors for occupational safety, in NR/L2/SIG/11201, Module B6;

d) guidelines on the application of different types of circuit in the relevant parts of this standard;

e) the typical circuits listed in NR/GN/SIG/CAT005; and

f) the relay specifications listed in NR/LS/CAT006.