scope:

2.1 Applicability

This standard applies to the traction return circuit and associated earthing and bonding that form part of the a.c. electric traction energy subsystem and installations

that can be endangered by the traction power system. It applies to:

a) connections to the traction return circuit of the electric traction in a.c. electrified railways;

NOTE The traction return circuit itself is part of the electric traction energy subsystem design.

b) wholly conductive or partly conductive structures or parts in the overhead contact line zone (OCLZ) and/or current collector zone (CCZ);

c) electrical installations fed by the contact line system;

d) installations that that are outside the OCLZ and outside the CCZ but which can be endangered by the traction power supply system.

2.2 Earthing and bonding system interfaces

The earthing and bonding system under consideration can be further described and structured into subsystems. The principal railway subsystems and the electrical

interfaces related to earthing, bonding and the traction return circuit are described in high-level terms in BS EN 50562 and in Table 1 of this standard.

2.3 Exclusions from scope

This standard does not apply to:

a) matters concerning electrical safety and earthing within distribution network operator (DNO) or transmission network operator (TNO) traction supply

substations;

b) traction switching stations themselves other than the RCBB connection to the traction return circuit;

c) workshops, depots, train wash facilities and similar facilities (unless they are located in the OCLZ and/or CCZ);

d) a.c./d.c. traction interfaces;

e) the bonding required for train detection;

f) rolling stock, rail vehicles or plant that operate on the electric traction energy subsystem;

g) maintenance of the traction return circuit;

h) operational procedures.

Purpose

The purpose of this standard is to define the fundamental design principles that support the development of earthing and bonding system design to meet legislative

requirements and to achieve safety, economy and performance. This standard acts as the requirements as obliged in:

a) Commission Regulation (EU) No. 1301/2014;

b) BS EN 50122-1;

c) Energy Networks Association Engineering Recommendation (ENA ER) G12;

d) BS 7671;

e) RIS-1855-ENE; and therefore, supports compliance with the Health and Safety at Work Act 1974 and the Electricity at Work Regulations 1989.

This standard provides a common strategy to demonstrate compliance and optimize the design of railway subsystems in line with the requirements of NR/L2/ELP/27275,

but is not intended to reiterate legislation and governing standards.