EARTHING & BONDING – CVL E&B
Transport for Wales
Enable Infrastructure were engaged in a self-delivery contract arrangement with Transport for Wales to deliver the installation of Earthing & Bonding (Package 12) on both the ABD and THT Lines. The bonding covered trackside bonding for both sections, and also station bonding which was varied into the contract during the works. There were 4 major stations, and 8 minor stations where all bonding was completed and signed off. Enable also had civils works varied into the contract to facilitate bonding, including major bonding and civils works at the new Porth transport hub.
The project
The main scheme project was undertaken by the Enable Power Systems team, with additional civils works being undertaken by the civils teams based in Wales.
The project has required several interfaces, including closely working with the Transport for Wales appointed maintainer, Amey, who undertook all design works on behalf of Transport for Wales, with the assistance of Enable engineers during IDC/IDR process.
The works were carried out as a part of the Core Valley Lines electrification project, with Enable’s specific scope being carrying out Earthing & Bonding works on AC Electrified Lines.
Enable undertook initial site surveys for 2 weeks on both the ABD and THT line, spanning over 18 ‘Construction Units’. During these surveys all proposed bonding locations were reviewed, with Enable using their experience and expertise to provide additional bonding locations to Amey designers.
The electrical works included bonding of all assets, from cross-track bonding to Points heating bonding, to the bonding of existing assets such as mesh fences.
The civil works carried out including installation of ducting, troughing installation, modification of existing trenches / trough routes. This enabled a smooth install for all bonding at stations and ensured that all installs are future-proof, with plenty of spare capacity for any future works.
The challenge
- Competency of OLEC 3.5 is rare in staff, so ensuring all staff were competent prior to any works being carried out proved difficult.
- Time constraints due to short possessions were challenging as there was a maximum of 3.5 hours per night.
The solution
- Enable Power Systems engaged with Enable Resourcing to ensure all 4 supervisors associated with the project carried out the relevant training which resulted in there being 1 x OLEC 5.0 staff and 3 x OLEC 4.0 staff.
- All plant and materials were delivered to the relevant access points prior to possessions starting, and extensive planning was carried out to split teams up so that the full capacity of bonds were completed in the short timeframe. This ensured maximum efficiency from the site team.
The deliverables
CIVILS
- Duct installation
- Trough installation
- Fencing installation
- Core-drilling for ducting
- Trenching / Excavations
ELECTRICAL
- Installation of Cross Track Traction Bonding to OHLE Structures
- Installation of Cross Track Traction Bonding to Designated Earth Points (DEP)
- Installation of Cross Track Traction Bonding to Traction Switching Stations (TSS)
- Installation of Cross Track Traction Bonding to Feeder Stations
- Installation of Bonding to Metallic Equipment on Station(s)
- Installation of Continuity Bonding Over Rail Joints (IRJ’s)
- Installation of Bonding to Lineside Assets including but not limited to the following
- All metallic assets will be bonded back to the return screen conductor (RSC) using Pfister T Piece connection.
- All cross-track traction bonding will be connected to either a wraparound or post mounted spider plate, as this acts as a common bonding connection for the aerial earth wire and / or return screen conductor, all wraparound spider plates will be installed by the OLE contractor.
- All bonds are to be unique labelled for easy identification
- All bonding works will be carried out in in accordance with isolation procedures to BS7671 and Electricity at Work Regulations
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