Understanding Induced Voltage Risks Between HV Cables and Buried Pipelines

As electricity networks expand to support renewable energy projects, Battery Energy Storage Systems (BESS), and utility infrastructure upgrades, it is increasingly common for high-voltage cable routes to cross or run parallel to existing buried pipelines.

These pipelines may carry fuel, gas, water, or other critical utilities, requiring careful consideration during the design process. One of the key engineering challenges in these situations is the assessment of induced voltages. While often overlooked during route planning, electromagnetic coupling between power cables and metallic pipelines can create touch voltage, corrosion, and safety concerns if not appropriately assessed.

Why Induced Voltages Occur

Whenever current flows through an HV cable, it generates a magnetic field. If a metallic pipeline is located nearby, a voltage can be induced onto the pipeline through electromagnetic coupling.

The magnitude of this induced voltage depends on several factors:

• Separation distance between the cable and pipeline

• Length of parallel route

• Cable configuration

• Load current

• Earth fault current levels

• Soil resistivity

• Earthing arrangements

Although induced voltages under normal operating conditions are often relatively low, fault conditions can produce significantly higher values and must be assessed as part of the cable system design.

Typical Scenarios Requiring Assessment

Induced voltage assessments are commonly required where:

• HV cable routes run parallel to metallic pipelines

• Cable routes cross fuel or gas pipelines

• New substations are installed near pipeline infrastructure

• Joint bays and earthing systems are located close to pipelines

• Utility providers request evidence that electrical interference has been adequately considered

In utility, renewable energy and BESS projects, these assessments are increasingly becoming a standard stakeholder requirement during the design approval process.

Crossing Arrangements

Where practical, cable and pipeline crossings should be designed to minimise electromagnetic interaction and construction risk.

Good engineering practice generally includes:

• Crossing at or close to 90°

• Maintaining adequate vertical separation

• Installing cables within suitable ducts

• Avoiding direct contact between pipelines and cable systems

• Ensuring future maintenance can be safely carried out on either asset

Crossing geometry can have a significant influence on induced voltages, with shorter interaction lengths generally resulting in lower levels of coupling.

The Importance of Fault Conditions

While normal operating currents are present continuously, the highest induced voltages usually occur during earth fault events.

When a fault occurs, large quantities of current may return through cable screens, earth conductors and the general mass of earth. These currents can create temporary voltage rises on nearby metallic infrastructure.

For this reason, assessments should consider:

• Maximum system earth fault levels

• Fault duration

• Cable bonding arrangements

• Earthing system design

• Pipeline location relative to substations and joint bays

A design that appears acceptable under normal running conditions may require further investigation when fault conditions are taken into account.

Earthing and Joint Bay Considerations

One area frequently overlooked during route development is the location of cable joint bays and associated earthing systems.

Ground Potential Rise (GPR) can occur during fault conditions, resulting in elevated voltages around earthing electrodes. If pipelines are located nearby, touch potential risks may need to be assessed.

Good practice includes:

• Locating earthed joint bays away from pipelines where practical

• Assessing touch voltages during fault conditions

• Reviewing earthing electrode arrangements

• Ensuring compliance with relevant industry standards and utility requirements

For many developers, these assessments form part of the wider HV cable design process and should be considered alongside thermal rating studies, sheath bonding design and installation engineering.

Relevant Standards and Guidance

A number of standards and guidance documents may be relevant when assessing interactions between HV cable systems and buried pipelines, including:

• ENA ER S34

• BS EN 50443

• BS EN 50522

• UKOPA guidance documents

• IEC and CIGRE publications relating to electromagnetic interference and earthing systems

The applicable requirements will vary depending on project-specific conditions, system voltage, pipeline owner requirements and network operator standards.

Practical Design Advice

From a design perspective, the most effective approach is to consider pipeline interactions during the earliest route development stages.

Simple decisions such as:

• Increasing separation distance

• Optimising cable configuration

• Adjusting crossing angles

• Relocating earthing points

can significantly reduce induced voltage levels and remove the need for costly mitigation solutions.

Early engagement with pipeline operators and utility stakeholders can also help prevent delays during project approval and construction.

Conclusion

As electricity networks continue to expand, interactions between HV cable systems and existing buried infrastructure are becoming increasingly common. Induced voltage assessments play an important role in demonstrating that new installations can operate safely alongside fuel, gas, water and other metallic pipelines.

By considering electromagnetic coupling, fault currents, earthing design and route geometry at an early stage, engineers can develop robust, compliant designs that minimise risk and avoid unnecessary construction complexity.

At Cable Engineering Ltd, we regularly support utility, renewable energy and BESS developments with HV cable design, thermal rating studies, sheath bonding assessments, earthing design and specialist cable system engineering. Early technical assessment of pipeline interactions can help identify potential issues before they become project risks, reducing both programme delays and construction costs.