Other Conductivity Precautions

Vehicular and Mechanical Equipment

Any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines must be operated so that a clearance of 10 ft (305 cm) is maintained.

If the voltage is higher than 50kV, the clearance must be increased 4 in (10 cm) for every 10kV over that voltage. However, under any of the following conditions, the clearance may be reduced:

• If the vehicle is in transit with its structure lowered, the clearance may be reduced to 4 ft (122 cm). If the voltage is higher than 50kV, the clearance must be increased 4 in (10 cm) for every 10 kV over that voltage.
• If insulating barriers are installed to prevent contact with the lines, and if the barriers are rated for the voltage of the line being guarded and are not a part of or an attachment to the vehicle or its raised structure, the clearance may be reduced to a distance within the designed working dimensions of the insulating barrier.
• If the equipment is an aerial lift insulated for the voltage involved, and if the work is performed by a qualified person, the clearance (between the uninsulated portion of the aerial lift and the power line) may be reduced to the distance given in Table S-5.

Vehicular and Mechanical Equipment (continued)

Employees standing on the ground may not contact the vehicle or mechanical equipment or any of its attachments, unless:

• The employee is using protective equipment rated for the voltage; or
• The equipment is located so that no uninsulated part of its structure (that portion of the structure that provides a conductive path to employees on the ground) can come closer to the line than the following:
  • For voltages to ground 50kV or below - 10 ft (305 cm);
  • For voltages to ground over 50kV - 10 ft (305 cm) plus 4 in (10 cm) for every 10kV over 50kV.

If any vehicle or mechanical equipment capable of having parts of its structure elevated near energized overhead lines is intentionally grounded, employees working on the ground near the point of grounding may not stand at the grounding location whenever there is a possibility of overhead line contact.

Additional precautions, such as the use of barricades or insulation, must be taken to protect employees from hazardous ground potentials, depending on earth resistivity and fault currents, which can develop within the first few feet or more outward from the grounding point.

Illumination

• Employees may not enter spaces containing exposed energized parts, unless employees are provided illumination that enables them to perform the work safely.
• Where lack of illumination or an obstruction prevents employees from seeing the work to be performed, employees may not perform tasks near exposed energized parts.
• Employees may not reach blindly into areas that may contain energized parts.

Confined or Enclosed Work Space

If an employee works in a confined or enclosed space (such as a manhole or vault) that contains exposed energized parts, the employer must provide, and the employee must use, protective shields, protective barriers, or insulating materials as necessary to avoid inadvertent contact with these parts.

Doors, hinged panels, and the like must be secured to prevent their swinging into an employee and causing the employee to contact exposed energized parts.

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