To review the main Contractor’s Earthing and Bonding concept design against IEC & EN standards and jointly develop strategies to support compliance leading to an executable and cost-efficient detailed design.


The HCMC Metro Line 1 in Vietnam is under construction incorporating a 1.5kV DC OCS system.  Appropriate earthing and bonding of the wayside equipment interfaced with the OCS, the negative return rail, the civil structure earthing and the lightning protection systems needs harmonization.


R&H Rail were responsible for but not limited to the following:

  • Reviewing the Earthing and Bonding concept design and providing recommendations that are compliant with IEC / BS specifications
  • Collaborate with Contractor’s team to develop strategies for a detailed design, taking into consideration:
    • OCS structures and Protection zones needed in case of OCS wiring failures
    • Lightning Protection Wire (PW)
    • Earthing of civil viaduct and handrail
    • Earth continuity of earthed equipment
    • Material type and mounting configuration of earthing conductors
    • Negative Return Rail and insulation thereof
    • Equipotential bonding of wayside equipment
    • Insulation of various equipment
    • DC stray currents mitigation
    • Material selection, positioning and mounting configurations of various equipment
    • Earthing of signalling points machines