In this article, Electrical Engineer, Jim Orosz, P.E. discusses the basics of safety as they relate to overhead utility lines, including a diagram of a typical joint pole layout.
Overhead Line Safety
The placement of different types of overhead lines on poles is governed by the National Electric Safety Code. Electric supply lines are placed in the upper area of the pole. Lines carrying the highest amount of energy or highest voltage are placed near the top of the pole with lower voltage lines placed below. Often a shield wire or static wire is strung above these lines to protect them from a lightning strike. Below the electric supply lines is a neutral space that separates the electric supply space from the communications space. This area protects communication workers from higher energy lines. The communication space consists of telephone, cable TV, fiber, and signal lines.
This figure illustrates a common allocation of space on joint utility poles in the United States; the allocation is similar in Canada except that cable television and telephone are sometimes lashed to the same supporting strand. Starting at the top and working down, facilities on the pole are allocated into three spaces:
- Supply Space
- Safety Zone Space (or Neutral Space)
- Communications Space
NESC Joint Pole Diagram
Basics of Overhead Line Safety
OSHA provides the following safety tips concerning overhead lines and equipment:
Electrical hazards can cause burns, shocks and electrocution (death).
- Assume that all overhead wires are energized at lethal voltages. Never assume that a wire is safe to touch even if it is down or appears to be insulated.
- Never touch a fallen overhead power line. Call the electric utility company to report fallen electrical lines.
- Stay at least 10 feet (3 meters) away from overhead wires during cleanup and other activities. If working at heights or handling long objects, survey the area before starting work for the presence of overhead wires.
- If an overhead wire falls across your vehicle while you are driving, stay inside the vehicle and continue to drive away from the line. If the engine stalls, do not leave your vehicle. Warn people not to touch the vehicle or the wire. Call or ask someone to call the local electric utility company and emergency services.
- Never operate electrical equipment while you are standing in water.
- Never repair electrical cords or equipment unless qualified and authorized.
- Have a qualified electrician inspect electrical equipment that has gotten wet before energizing it.
- If working in damp locations, inspect electric cords and equipment to ensure that they are in good condition and free of defects, and use a ground-fault circuit interrupter (GFCI).
- Always use caution when working near electricity.
Electric Utility Forensic Investigations
Our electric utility experts investigate issues related to line contacts, downed lines, clearance adequacy, and protective device performance. We evaluate equipment installations in accordance with National Electrical Safety Code (NESC), as well as maintenance and repair issues.
As a Major in the U.S. Army Reserve, working with FEMA on disaster relief, a West Point graduate in electrical engineering, and an accomplished Professional Engineer in the private sector, Jim is uniquely qualified to investigate electrical safety matters.
For more than ten years Jim worked in engineering and engineering management positions with Consolidated Edison Incorporated. During this time he was responsible for the safety and reliability of the electrical power distribution system, which included conducting inspections of the distribution system, development of test specifications for underground cables, and managing maintenance on the network.