scope:

Introduction

SSI equipment to BRB specification 1900 has been designed to operate satisfactorily in the environmental conditions of the conventional signalling equipment it replaces.

SSI equipment meets the relevant sections of BR specification 967 "Environmental Conditions for Railway Signalling Apparatus"; a CI meets the requirements of BR Specification 967, Category C and is therefore suitable for accommodating in a conventional relay room or signal box environment.

The power dissipation of SSI equipment is low and unless an excessive temperature rise would be caused by non-SSI equipment, there is no requirement for a controlled environment in an SSI equipment room although reasonable freedom from dampness and dust and a suitable level of security shall be provided.