Scope of Contestable Works
Workstream
Design & Acceptance
DNO Responsibilities
- Produce detailed network extension design
- Obtain adopting operator approval
IDNO Responsibilities
- Produce parallel detailed design for IDNO assets
- Secure adopting operator acceptance
Workstream
Civil Engineering
DNO Responsibilities
- Excavate off /on site cable trenches & joint holes
- Install ducts, draw ropes, bedding, blinding & marker tape
- Full reinstatement
IDNO Responsibilities
- Mirror civil scope for IDNO cable routes & joint bays
Workstream
Cabling
DNO Responsibilities
- Supply, lay & record HV mains from point of connection (PoC) to depot intake
IDNO Responsibilities
- Supply, lay & record HV mains from PoC to three on site substations
Workstream
Substation Buildings
DNO Responsibilities
- Supply & install single GRP enclosure
- Cast reinforced concrete plinth
IDNO Responsibilities
- Supply & install three GRP enclosures
- Cast three compliant plinths
Workstream
Primary HV Equipment
DNO Responsibilities
- Stand alone ring main unit (RMU)
IDNO Responsibilities
- 11 kV extensible switchboard (1 × switched incomer, 2 × outgoing CBs)
- Three 2 MVA package substations: RN2d relay protected RMU → 2 MVA 11/0.433 kV transformer → 3200 A ACB feeder pillar
Workstream
Earthing
DNO Responsibilities
- Install substation earth mat to NPG standards
IDNO Responsibilities
- Install earthing to bespoke design for all three substations
Workstream
Project & Stakeholder Management
DNO Responsibilities
- Plan, supervise & quality assure all DNO tasks
- Coordinate to energisation & adoption
IDNO Responsibilities
- Plan, supervise & quality assure all IDNO tasks
- Coordinate to energisation & adoption
- Seamless Integration: DNO and IDNO design packages aligned, achieving first time technical acceptance.
- Future Proof Capacity: Three 2 MVA package substations give Stagecoach scalable headroom for additional chargers or battery storage integration.
- Rapid Delivery: Trench and duct works sequenced to minimise depot disruption, allowing normal bus operations throughout construction.
- Compliance & Safety: All earthing installed to NPG and BS EN 50522 standards; full test results recorded before handover.
- Successful Energisation: HV switchgear commissioned, substations adopted, and power on stream ahead of charger installation schedule.
Lessons & Best Practices
- Early Dual Design Review: Parallel scrutiny by DNO and IDNO shortened acceptance cycles.
- Single Excavation Strategy: Coordinating DNO and IDNO trenching reduced civil costs and reinstatement time.
- Modular Package Substations: Factory tested units accelerated site works and simplified future maintenance.
- Stakeholder Coordination: Weekly joint progress calls kept Stagecoach, equipment OEMs, and regulatory bodies aligned to energisation milestones.
Impact
The new HV infrastructure empowers Stagecoach Rotherham to roll out a 100 % electric bus fleet, cutting local emissions and supporting South Yorkshire’s clean air goals. The project showcases how contestable works—shared between DNO and IDNO—can deliver cost effective, future ready power solutions for large scale transport electrification.
