Introduction: The JW420 Bulk Oil Circuit Breaker is likely to see a number of years of further service beyond its original design life due to its anticipated asset life being increased from 45 to 55 years by Asset Policy. There are currently 130 JW420 circuit breakers installed on the system. The JW420 design was originally installed in the 1960s and as such was not designed with modern health and safety requirements in mind. If National Grid intends to maximise the life of these assets then ensuring that they can be maintained in the safest way possible is paramount.

Objectives: The aim of this project is to provide as safe a working environment as possible for maintenance activities carried out on JW420 Bulk Oil circuit breakers. The aim is to ensure the improved maintenance tools and techniques are used across Maintenance Delivery Electricity (MDE) by further developing solutions and techniques that have been partially developed and used locally in the past. These include developing the following:

• 2 light weight access benches

• A light weight rear access working platform connecting the 2 benches to allow 3 side access to the primary contacts

• A temporary 1kg step arrangement to allow access to the top damper plug

• Temporary flooring for basic maintenance

• Temporary platforms for major maintenance

• Turbulator manual handling device

• Primary contact closing gag.