Solution Summary: Using Live-Line Tools
Live-line tools provide insulation between line workers and live parts or other conductors while maintaining a minimum approach distance from live powerlines.
Using live-line tools are safe work practices that can provide insulation between line workers and live parts or other conductors. Live-line tools offer solutions for performing high-voltage live-line work while maintaining a minimum approach distance from live parts. These live-line tools can be used when working on ladders, booms, or elevated work platforms and can be used on all types of poles (e.g., wood, steel, composite, and concrete).
Live-line tools are used for high-voltage operations. All tools are insulated, ideally with fiberglass or FRP (fiberglass-reinforced plastic), and filled with closed-cell foam to prevent moisture and dust from entering and to provide ultimate protection. These tools are available in a variety of forms and can be used in any high-voltage operations, including line repairs, installation, maintenance or removal.
Strict maintenance and testing are required to check for any disturbance in the tool that can be a danger to the user’s safety. Maximum usage voltage per foot of length for wooden live-line tools is 75 kV, and 100 kV for fiberglass live-line tools. All live-line tools must meet IEEE 516, IEEE 978, ASTM F2522, and ASTM F711 standards, as well as other standards depending on the specific tool. Live-line tools can be categorized into several different forms: Hot Sticks, Sectionalizer Kits, Insulated Links, Rescue Hooks, Discharge Hooks, Insulating Hand Tools, Cutter Sticks, and Clamp Stick/Shotgun Sticks.
Hot sticks are made of insulated fiberglass poles or FRP (fiberglass reinforced plastic) and are usually filled with closed-cell foam. They have an epoxy coating to protect from weathering. These sticks vary in length and can extend to high-reach areas. The sticks can have permanent ends or universal ends. Hot sticks must be tested to conform to ASTM F711 requirements.
Sectionalizer kits are used for temporary disconnects to isolate a section of line when there is a disruption or interruption in the circuits as a result of pole failures, insulation failure, or conductor failure. They isolate sections of lines that are in trouble without cutting off service to the balance of the circuit. A sectionalizer kit can be installed and removed with other live-line tools such as hot sticks, using the take-up device to hold the strain of the line, install the section, and then cut and clear the conductor.
Insulated links are placed between energized conductors and also can be used on ropes, hoists, and blocks. They have dielectric properties if a strap becomes contaminated during field use.
A rescue hook consists of a fiberglass pole with a waist-sized, heat-treated hook on the end used for pulling linemen out of a hazardous situation. This hook is especially useful when a line worker is injured and confined in an area from which it is hard to escape.
This hook eliminates a static charge after de-energizing. It de-energizes any voltage-retaining components before maintenance begins. It usually comes with a resistor to help get rid of initial surge current.
IMPORTANT: As described by OSHA 1910.269, discharge hooks are not to be used as grounding tools and carry no fault duty rating.
Insulating Hand Tools
These tools have insulated stick handles and are much shorter in length than hot sticks. They include a variety of tools, all with fiberglass handles filled with closed-cell foam.
Side Arms and Transfer Arms
Side arms and transfer arms are temporary parts for a live-line system. They can be used to help change poles, insulators, or cross arms. They can hold energized conductors for maintenance or replacement of poles or insulators. They have wire holders, as well, and can be used when repairing existing conductors.
Cutter Sticks are used to cut large-gauge cables and conductors using a self-hydraulic system. These sticks must conform to ASTM D877 requirements.
Clamp Sticks/Shotgun Sticks
Clamp sticks/shotgun sticks are used to grip and lock onto cables and lines for control and movement. They must meet ASTM F1825 Standards.
Electrical hazards are among the main construction industry hazards that cause serious injuries and death. Contact with electric current is a major cause of injury and death among construction workers (Janicak 2008). In 2012, the Census of Fatal Occupational Injuries (CFOI) data produced by the Bureau of Labor Statistics (BLS) indicated that contact with electric current was the fourth leading cause of work related deaths—after falls, transportation incidents, and contact with objects and equipment (BLS 2012). Electricity can cause electric burns, electrocution, shock, arc flash/blast, fires and explosions. One of the major causes of an electrocution hazard is contact with overhead power lines and energized sources. Overhead power lines are particularly hazardous since they carry high-voltage electricity. Although electrocution is considered the main risk, other important hazards of working near or on high-voltage lines include electrical shock, burns, and falls to lower levels. These types of hazards happen when the body becomes part of the electric circuit, whether by direct contact with an energized source or by contact with a conductive material that has become energized. The severity of the electrical hazard depends on several factors, including the length of exposure time, energy deposited into the body, the pathway through the body, wetness or dryness of the surface and the amount of current. The best and preferred method of control is to keep a safe distance from power lines. Table 1 shows the minimum safe distance for various line voltages.
Table1. minimum powerline clearance distances (Source: 29 CFR 1926.1408(h))
Live-line tools do not completely eliminate the risk of working with high voltage operations, but using them carefully will greatly reduce the risk of electrocution and shock. The appropriate PPE must be used when using live-line tools. In high-voltage operations, primary shock protection is provided by live-line tools that have sufficient length to provide a safe distance between the worker and live parts.
How Risks are Reduced:
Insulating sticks and other live-line tools provide electrical insulation between live lines and line workers and other sources of electricity, while always maintaining a minimum approach distance from any energized lines.
Effects on Productivity:
By using live-line tools, workers will be able to maintain safe distances while working on energized lines. Moreover, there is no need to spend time and money to contact utility companies to de-energize lines and then follow all grounding processes to ensure de-energizing (it should be noted that de-energizing is the safest route for working around electrical equipment/lines). Therefore, using live-line tools can reduce the risks of accidental contacts and improve productivity. Generally, when workers feel safe working on live lines, they will be more productive.
All live-line users must be trained before using these tools. Hand guards must be firmly secured to the insulated sticks to prevent any unauthorized movements during work, inspection, transport, and cleaning.
Maintenance and testing:
- Live-line tools require a comprehensive in-service maintenance and dialectic-testing program. All these processes are in accordance with OSHHA 1910 and IEEE Std 978-1984 for visual inspection, cleaning process, waxing and testing requirements.
- Exposure to outside weather conditions (sunlight, heat, cold) can greatly deteriorate the fiberglass insulation of the tools, making them unusable. Keeping them in hard plastic storage containers away from any stress is the best option for the extended life span of the tool.
- Live-line tools must be kept clean of any dust and contamination that may cause slight discharges.
- Live-line tools are designed to withstand 100,000 volts per foot (in service they are tested at 75,000 volts). OSHA requires live-line tools to pass a test of 100,000 volts for a duration of 5 minutes (ASTM F711). A portable tester can be used, but only testing 75,000 volts per foot. Performance tests are required at least every two years. If defective conditions are noticed before this period, it would be safe to test the tool again before using live-line tool.
- When live-line tools are in use, they are exposed to physical stress and damage. The actual fiberglass-insulated handle/pole may be nicked, stretched, scratched, wet, or experience any other abrasion that can decrease the insulation of the tool and lead to a hazard. The tools must be checked to ensure that they are damage free and in good condition for use.
Behzad Esmaeili, Ph.D. - University of Nebraska- Lincoln
Sogand Hasanzadeh - University of Nebraska- Lincoln
Pouya Gholizadeh - University of Nebraska- Lincoln
Erik Bruening - University of Nebraska- Lincoln
Brett Farquhar - University of Nebraska- Lincoln
To obtain information, visit http://www.macronsafety.com/ or contact 1-916-905-6535
To obtain information, visit http://www.hfgp.com or contact 1-269-945-9541
Salisbury by Honeywell
To obtain information, visit https://www.salisburybyhoneywell.com or contact 1-877-406-4501
Hubbell Power Systems
To obtain information, visit http://www.hubbellpowersystems.com or contact 1-573-682-5521