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Cranes and derricks used in construction must remain at least 20 feet away from lines up to 350 kV, and 50 feet away from lines greater than 350 kV, if operated up to the equipment’s maximum reaching radius. In addition, the operator must implement specific encroachment prevention precautions. (See sidebar.)

As voltage increases, clearance distances also increase. Consult the OSHA regulations at for specific clearance requirements. NOTE: Virginia and North Carolina have State Occupational Safety and Health Plans. For further information visit the State OSHA Program website at and click on your state.

  • Once you have established the required clearance, clearly mark a boundary with tape, signs, or barricades.

If any part of the equipment can get closer than 20 feet (for lines up to 350 kV) or 50 feet (for lines greater than 350 kV) contact Dominion well in advance so any necessary facility protection arrangements can be made, and implement encroachment prevention precautions.



Encroachment Prevention Precautions:

  • Conduct a planning meeting with the operator and other workers.
  • Tags lines must be non-conductive (if used).
  • Erect and maintain elevated warning line, barricade, or line of signs, in view of the operator at 10’ from the power line.
  • If the operator is unable to see the warning line, a dedicated spotter must be used.

In addition to the above precautions, the operator must implement one of the following:

  • Use a proximity alarm, designed to give the operator sufficient warning to prevent encroachment.
  • Use a dedicated spotter who is in continuous contact with the operator.
  • Use a device that automatically warns the operator to stop (range control warning device).
  • Use a device that limits the range of movement, set to prevent encroachment.
  • Use an insulating link between the end of the load line and the load.