EWT - Overhead Lines

The Occupational Safety & Health Administration (OSHA), “…has estimated that an average of 12,976 lost-workday injuries to and 86 fatalities of electric power generation, transmission, and distribution employees occur annually. Using these figures, OSHA has also estimated the number of injuries which could be prevented by the new regulations. Taking into account such factors as existing regulation and the differences in training levels among utilities, OSHA estimated that 1,634 lost-workday injuries and 61 deaths could be prevented each year…”

Overhead work is inherently dangerous. When workers can’t eliminate hazards, they must reduce and control them as best as they can. When installing or removing overhead lines, workers must protect each other against hazards that could expose them to electrocution. Overhead line supporting structures are obvious starting points for both physical and electrical hazards. Poles, towers, and other elevated structures must be strong enough to withstand the stresses that will be placed on them. If a structure cannot withstand the load, it must be reinforced using devices like bracing poles and guy wires.

When setting, moving, or removing a pole near any exposed live conductor, the pole must not contact the conductor; contact might energize the pole and/or damage the conductors, creating multiple hazards for a work crew. Also, when you setting, moving, or removing a pole near any exposed live conductor, workers must use appropriate personal protective equipment (PPE) and insulated devices.

Lineworkers should not contact a pole with uninsulated parts of the body; that could provide a path to ground, electrocuting them. For the same reason, they must protect themselves against touch and step potential differences.

Here are some tips for staying safe while poles and towers are in motion…

Secure the Load

When hoisting and setting a tower section into place, keep the loadline attached to the load until everyone is certain the load is fully secured.

Stabilize the Load

Use tag lines (or similar devices) to maintain control of tower sections while raising or positioning them. Make sure the load stays balanced and manageable: not top-heavy, and not too bottom-heavy.

Stay Clear Below

No one should be in the “drop zone” under any tower or structure that is being moved or worked on. Clearing out the drop zone protects the crew from any falling tools, cables, or structural components. The only exception is when someone must assist employees working above.

Rough weather can make overhead work much more dangerous. Safety pros must stop work under weather conditions that would make the work hazardous—unless performing emergency power restoration. Also, after a thunderstorm, workers must not begin or resume work for at least thirty minutes after hearing the last thunderclap. Other examples of hazardous weather include: high winds that could reduce minimum approach distances and snow or ice storms.

To Prevent Live Contact

Use the tension stringing method, barriers, or other physical measures to prevent conductors and cables from contacting live lines or equipment.

Tugger Failure

Workers must be protected against equipment failures that could energize wires or cables as they work with them.

Wire/Cable Failure

Stay alert for any failure of the wire or cable that’s being pulled.

Failure of Installed Lines/Equipment

Watch out for failure of any previously installed lines or equipment.

Set Reclosers to One-Shot

When pulling over energized lines, activate “one-shot” operation to prevent breakers from automatically reclosing after any fault.

If installing new lines parallel to existing, live lines, workers must anticipate and control any induced voltage from these energized lines’ electromagnetic fields.

Protecting Against Induced Voltage:

• If installing new lines parallel to existing, live lines, anticipate and control any induced voltage from these energized lines’ electromagnetic fields.
• Determine the induced voltage
• Unknown voltage? Assume as hazardous
• Ground every two miles
• Remove grounds last
• Ground at work sites and dead ends
• Bond before splicing

Pulling Lines Safely:

• Be very careful when operating reel-handling equipment, including pulling and tensioning devices. Broken cables have severely injured and killed lineworkers.
• Make sure equipment is leveled and aligned.
• Don’t exceed the ratings of any equipment. This includes stringing lines, pulling lines, rigging, hoists, conductor grips, and load-bearing hardware and accessories.
• Don’t use conductor grips on wire rope, unless a grip is specifically designed for this purpose.
• Be sure to maintain reliable communications between the reel tender and the pulling-rig operator.
• Operate the pulling rig only when it is safe to do so.
• No one should be present below overhead operations. The only exception is when someone must be present to guide the stringing sock or board over, or through, the stringing sheave.