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Elevated Neutral-to-Earth Voltage, Contact Voltage, and Other Perceptibility Concerns for Humans and Animals

Project Results and Status

To date, EPRI research in stray and contact voltage has resulted in about 50 technical documents that have been distilled in various forms and posted on this website. These include:

  • PowerPoint presentations
  • Technical Commentaries on various related topics
  • Case Studies
  • Industry updates

Contact Voltage Roadmap

The intent of EPRI’s initiatives surrounding the topic of contact voltage is to provide unbiased credible support to the proliferation of solutions related to contact voltage scenarios and to fill in gaps in existing research.

Understanding the Issues

Before developing a plan of action, it is important to first identify the range of concerns associated with stray and/or elevated voltage potentials. With a better understanding of the concerns and the magnitude of the problems, it is easier to identify areas where concerns have already been adequately addressed and areas where supplemental information and/or research can support the efforts already completed.

In all, we have identified 15 different concerns and topics of interest in five different focus areas. These concerns and topics of interest are:

  1. Personnel safety related to touch potentials (mostly worker concerns related to induced voltages onto gas and water lines)
  2. Animal contact area related to health and productivity impacts
  3. Residential swimming pool, hot tub, and other shock hazards related to metallic objects
  4. Power circuit resonance conditions creating magnified neutral-to-earth voltage potentials
  5. Impacts of power-line carrier communication technologies and other transient switching devices on the magnitudes of stray voltage
  6. Voltages on rail, gas, and water line installations near power line right of ways
  7. Different opinions on specifications of measurement equipment, measurement protocols, and measurement durations
  8. Harmonic neutral currents interfering with telecommunication circuits
  9. Modeling and simulation challenges for complete distribution circuits
  10. Contributions of transmission lines to elevated NEV levels at animal contact areas
  11. Harmonic neutral currents interfering with the operation of signals at railroad crossings
  12. Adequate understanding of impacts and benefits of mitigation techniques and of mitigation hardware
  13. Energization of metallic objects in urban areas
  14. Development of representative models for complex soil and electric distribution configurations for underground distribution systems
  15. Nonlinear impacts of voltage waveforms and voltage magnitudes on humans and animals

Although research has been conducted in some of these identified areas, there tends to be a lack of consistency in terms of understanding how significant the impacts are and whether or not a specific measured value is at or below a specified “level of concern.”

The EPRI R&D Toolkit

EPRI is maintaining this single information repository and arsenal of tools suitable to address any area of interest related to contact voltage. Annual EPRI research focuses on five areas:

  1. Testing and Measurement
  2. Modeling and Simulation
  3. Information Services
  4. Technology Development
  5. Impact Assessments

To support the information resulting from research, EPRI conducts workshops, conducts site investigations, and maintains a training resource at the test facility in Lenox, Massachusetts, which includes an in-ground swimming pool, an urban contact voltage test range, and an overhead test range to generate neutral-to-remote-earth voltages.