Hazards and Safety in High Voltage Power Lines

Types of Sub

What are high voltage transmission lines?

Transmission lines or overhead Power Lines transmit electricity from the generating stations to other places such as large industries or to distribution networks from where the electricity is further supplied to different consumers.

  • EHV (Extra-high voltage) lines: EHV lines are those transmission lines whose voltage level is between 230kV to 1000kV.
  • UHV (Ultra-high voltage) lines: Those transmission lines whose voltage level is above 1000kV are categorized as UHV lines.

Structure of transmission tower

A Transmission tower consists of the following constructional parts:

  • Cross arms: They hold the main conductor lines. The dimensions of cross arms depend upon the voltage level on which the transmission line is to be operated.
  • Cage: This portion holds the cross arms of the tower. It lies between the peak and body of the tower.
  • Tower body: The portion of the tower between the bottom cross arms and the ground is known as the tower body. The purpose of the tower body is to provide adequate clearance between the ground and conductors.
Structure of transmission tower

Important terms

  • Right of way: It is defined as the land across the transmission lines which is set aside to provide a safe margin for the nearby areas. This corridor is used by relevant authorities to repair, construct, or maintain transmission lines and towers.
  • Safe distance: Safe distance is the distance from the transmission tower to the end of the corridor defined by the right of way. It can also be named as a border zone.
  • Sag: It is defined as the difference between the level of point of support and the lowest point of the conductor.
  • Ground clearance: The distance from the lowest point of the conductor to the ground is known as ground clearance.

Dangers of high voltage power lines

Electricity can be very dangerous for surrounding. Click here to read the number of hazards related to high voltage power lines.

Health hazards due to overhead high voltage power line

The concern for health hazards related to overhead power lines was first raised in 1979. In this study, it was discussed that electromagnetic radiations emitting from powerlines can cause childhood leukemia. Some researches stated that power lines can cause cancer and other critical health problems and the closer we get to HV overhead lines, the more dangerous the electromagnetic radiations become.

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Step potential and touch potential

Step potential is created when a fault occurs in power lines and current from the conductor starts to flow towards the earth. The voltage level of the area surrounding the grounding point is not uniform due to non-uniformity in resistivity of soil, so a potential difference is created there.

Power lines safety rules and precautions

​There are some precautions which must be followed to avoid electrical hazards and risks:

  • Animals should never be tied to a transmission tower or pole as it can risk their life.
  • Any object made up of metal or conducting material should not be thrown on overhead lines.
  • During rain, towers or poles must not be touched by any person because the tower body becomes energized due to the conductivity of water.
  • During storms or strong winds, we should keep a safe distance from powerlines as live conductors may accidentally fall over a person.
  • If a person sees any spark on overhead live conductors, his first responsibility should be to inform the relevant authorities to avoid any accident.
  • Any construction work should not be carried out under or near HV power lines.

Conclusion

Electricity is a great blessing for us as it has advanced and automated our life to an infinite extent. But along with these benefits, electricity is also very dangerous at the same time. It creates a number of hazards and health issues thus endangering our life. If we properly follow the safety rules, standards, and precautions, then we can reduce and even eliminate the risks and hazards caused by electricity. Conclusively, it’s up to us that either we make our life comfortable or full of risks.

About The Author

Abdur Rehman is a professional electrical engineer with more than eight years of experience working with equipment from 208V to 115kV in both the Utility and Industrial & Commercial space. He has a particular focus on Power Systems Protection & Engineering Studies.

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