scope:

This document supplies additional guidelines for arc, arc splash and thermal protection on rolling stock owned or leased by the Company, in order to provide a safe environment for users and operators. It applies to a 4-rail d.c. traction supply where neither pole is normally bonded to earth, but either pole of which may occasionally become so. It also applies to vehicles that run for part of their schedule on National rail infrastructure where the traction supply system is 3rd rail 750Vdc and the negative traction supply is effectively bonded to one of the running rails. Guidelines regarding the materials used for this protection are also defined.

The expected users of this document are LU procurement agents, suppliers contracted under any subsequent specifications and technical staff within LU and Tube Lines.

Purpose

The purpose of this document is to provide additional guidelines to ensure that arcing from unprotected electrical cables and other defects that have the potential to cause high heat release do not cause a fire or smoke incident during the operation of the train.

The arc protection philosophy is to:

a) minimise the risk of arc initiation;

b) minimise the severity and duration of an arc;

c) contain an arc;

d) minimise the release of smoke, fumes and toxic products;

e) avoid saloon penetration; and

f) ensure arc extinction.

The thermal protection philosophy is to:

a) assess the level of protection required;

b) containment of heat, fire or smoke;

c) minimise the release of smoke, fumes and toxic products;

d) avoid saloon penetration; and

e) ensure fire/smoke extinction.