Measurement of Handle Forces for Crimping Connectors and Cutting Cable in the Electric Power Industry

Overhead and underground line work in the electric power industry is physically very strenuous and can expose workers to musculoskeletal disorders (MSDs), particularly in the upper extremity. Crimping compression connectors—such as sleeve connectors and lugs—and cutting cables are two of the most frequent tasks that line workers perform. Line workers at many utilities in the US crimp connectors and cut cable with long-handled manual tools. However, the actual magnitude of the forces applied to the handles of these tools is not known. The objectives of this laboratory study were to measure the forces applied to the handles of a manual press and a manual cutter in order to connect typical wire gauges and cut common cables, respectively. The handles of the manual press and cutter were attached to the drive cylinder and load cell of an Instrom Material Testing System, and peak forces exerted against the handles were measured. Results showed that the outer die of the manual press required about 50% more handle force than crimping connectors with the inner die location. The peak handle forces required to cut aluminum conductor cable as large as 2 cm diameter exceeded 500 N and were about 200 N greater than the peak forces to compress connectors manually. When the peak force data were compared to strength capabilities reported in the literature, less than 1% of the general population was found to have the maximum strength to manually make one crimp on a common overhead connector. Less than 1% and approximately 50% of the female and male general population, respectively, were found to have the maximum strength to manually cut a cable with a 2 cm diameter conductor. Handle force data from this study provide a biomechanical framework for explaining how the job demands of overhead and underground line workers could possibly cause MSDs. Relevance to industry Electric power utilities can review their work practices and tools in order to determine whether they can reduce the exposure of their workers to risk factors of MSDs, as well as reduce their cost of health care. Manufacturers of crimping and cutting tools can use the experimental approach in this study to measure the external forces required for their respective tools and then set quantitative force benchmarks to improve the design of their tools

A Biomechanical Evaluation of Overhead Distribution Wire Connection Methods in the Electric Power Industry

Ergonomic evaluation of tasks and subsequent interventions are in their infancy in the electric power industry, which experiences a high rate of musculoskeletal disorders (MSDs), such as shoulder tendinitis and carpal tunnel syndrome. One of the most strenuous tasks performed by line workers is connecting wires with a manual compression tool. Ergonomic teams have been established and subjective assessments have been conducted at some utilities across the U.S.; however, to the author\u27s knowledge, no previous studies have examined the biomechanical stresses from connecting wires with manual and battery presses. There is currently no information on the muscle loading experienced by the major torso and upper extremity muscles while connecting wires. The research conducted in this study addressed this research void by measuring the external forces required to connect wires manually and also muscle activity of the deltoid, flexor cligitorum superficialis, extensor cligitorum communis, and erector spinae. The results and recommendations from this study can aid safety and health professionals in the electric utility industry in their efforts to reduce the severity and incidence of MSDs afflicting overhead line workers. The target audience for this study is the electric power industry in the United States, and therefore the data and results are presented in standard English units

Four Assessment Tools of Ergonomics Interventions: Case Study at an Electric Utility\u27s Warehouse System

An ergonomics program was developed in a Midwestern electric utility warehouse system. Tasks problematic with respect to work-related musculoskeletal disorders (WMSDs) affecting both the back and upper extremities were identified and engineering controls were implemented. Quantitative analysis was performed on each task before and after ergonomics intervention to evaluate exposure to the risk of WMSDs. Four methods were used to evaluate the risk of exposure to injury before and after ergonomics intervention: the 1991 National Institute for Occupational Safety and Health (NIOSH) lifting equation, the Static Strength Prediction Program, the Lumbar Motion Monitor, and the Borg psychophysical assessment of effort. Results from applying these four methods to the reengineered tasks showed that the probability of low-back disorder risk factors was reduced by as much as 29%, the percentage of people capable of performing tasks was increased by as much as 90%, the NIOSH Lifting Index was reduced from above 2.0 to less than 2.0, and the psychophysical assessment of effort was consistently reduced from the “heavy or strong” range to the “light or moderate” range