Cross-Bonding

Cross-bonding is a critical electrical safety practice employed to mitigate induced voltages and circulating currents in metallic infrastructure, particularly in AC railway systems and buried pipelines. It involves deliberately connecting multiple conductive objects, like rails, pipes, or cable sheaths, at regular intervals. This interconnected network allows for the dissipation of fault currents, equalization of potentials, and reduction of the risk of corrosion and electric shock hazards. Effective Cross-Bonding requires careful planning and execution, considering factors like soil resistivity, current flow patterns, and connection integrity to ensure optimal performance and safety. It forms a cornerstone of infrastructure protection in high-voltage and high-current environments.

Cross-Bonding meaning with examples

• In railway systems, Cross-Bonding connects running rails and often other metallic components to provide a low-impedance return path for traction currents and fault currents. This mitigates voltage gradients and prevents dangerous step and touch potentials, especially in the event of a short circuit. Without Cross-Bonding, stray currents can cause corrosion and safety hazards.
• Utility companies utilize Cross-Bonding techniques to safeguard underground pipelines from induced AC voltages generated by nearby power lines. Connecting the pipes together helps to distribute the current and minimize the potential difference between different sections, thereby reducing corrosion and safeguarding pipeline workers and the public.
• When installing new high-voltage power cables, the metallic sheaths of the cables are often cross-bonded at strategic locations. This design minimizes the induced voltages along the sheath, reducing the risk of dielectric breakdown, improving cable life, and preventing excessive circulating currents that can waste energy.
• Telecom companies implement Cross-Bonding in their cable systems to neutralize inductive interference and to reduce the overall cable length required. By bonding the cable sheaths at regular intervals, they can minimize noise pickup from the environment and reduce the need for costly isolation strategies.
• During the construction of a new substation, the grounding grid and all metallic structures must be cross-bonded to ensure that all conductive parts are at the same potential during a fault. This ensures the safety of personnel and prevents equipment damage by providing a low impedance path for fault currents.