Ergonomic Interventions for Electricians in Fossil-Fueled Power Plants

1012570

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 PO Box 10412, Palo Alto, California 94303-0813 USA

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Ergonomic Interventions for Electricians in Fossil-Fueled Power Plants

1012570

Technical Update, December 2006

EPRI Project Managers G. Mezei J. Yager

DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITIES THIS DOCUMENT WAS PREPARED BY THE ORGANIZATION(S) NAMED BELOW AS AN ACCOUNT OF WORK SPONSORED OR COSPONSORED BY THE ELECTRIC POWER RESEARCH INSTITUTE, INC. (EPRI). NEITHER EPRI, ANY MEMBER OF EPRI, ANY COSPONSOR, THE ORGANIZATION(S) BELOW, NOR ANY PERSON ACTING ON BEHALF OF ANY OF THEM:

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ORGANIZATION(S) THAT PREPARED THIS DOCUMENT Marquette University

This is an EPRI Technical Update report. A Technical Update report is intended as an informal report of continuing research, a meeting, or a topical study. It is not a final EPRI technical report.

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CITATIONS This document was prepared by

Marquette University 1515 W. Wisconsin Avenue Milwaukee, WI 53233

Principal Investigators R. Marklin A. Stone

This document describes research sponsored by the Electric Power Research Institute (EPRI). This publication is a corporate document that should be cited in the literature in the following manner:

Ergonomic Interventions for Electricians in Fossil-Fueled Power Plants. EPRI, Palo Alto, CA: 2006. 1012570.

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ABSTRACT

The major tasks of electricians at a fossil-fueled power plant electric power utility are the installation, maintenance, and repair of electrical equipment that is located throughout the facility. While much of electrical work is planned, a considerable amount of work that electricians perform is repairing and replacing electrical equipment that may fail unexpectedly. Electrical work is physically strenuous and exposes electricians to musculoskeletal disorders (MSDs), such as low back, shoulder, and wrist injuries. The objectives of this three-year project are threefold. The first objective is to use biomechanical instruments and software models to quantitatively evaluate electrical tasks that pose medium to high risk of MSDs. The second objective is to develop an ergonomics process for electricians at a utility in the upper U.S. Midwest (hereby known as the central utility) and train these workers and supervisors so they can successfully sustain the ergonomics process. The third objective is to write an ergonomics handbook that will show in detail how common electrical work practices can be improved by modifications to equipment, tools, or methods. This handbook will aid safety and health professionals at electric power utilities across the United States as they strive to improve the occupational health of electricians who work in fossil-fueled power plants. Along with the establishment of an ergonomics process for electricians at the central utility, preliminary results include evaluation of three common electrical tasks and recommended ergonomic interventions. Future work will include sustaining the ergonomics process for electricians at the central utilitys fossil-fueled power plants and making quantitative biomechanical studies of two tasks that electricians perform.

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LIST OF FIGURES

Figure 4-1 An Electrician Kneeling to Work on an Electrical Box Located at Floor Level .........4-4 Figure 4-2 An Electrician Kneeling to Work on an Electrical Box Located at Floor Level .........4-4 Figure 4-3 An Electrician Working on an Electrical Box at an Appropriate Height....................4-5 Figure 4-4 An Electrician Working on an Electrical Box at an Appropriate Height....................4-5 Figure 5-1 Hand Crimper ..........................................................................................................5-4 Figure 5-2 Long-Handled Manual Press ...................................................................................5-4 Figure 5-3 Pump-Actuated Manual Press.................................................................................5-4 Figure 5-4 AC-Powered Pump with Hydraulic Press ................................................................5-5 Figure 5-5 Crimping a Connector Using a Long-Handled Manual Press..................................5-5 Figure 5-6 Crimping a Connector Using a Pump-Actuated Press.............................................5-6 Figure 5-7 Examples of Battery-Powered Presses for Crimping 3/0 AWG or Larger ...............5-6 Figure 5-8 Crimping a Connector Using a Battery-Powered Press...........................................5-7 Figure 6-1 An Electrician Lifting a Coil of Cable from a Cart ....................................................6-2 Figure 6-2 Coils of Cable on a Pallet ........................................................................................6-3 Figure 6-3 An Electrician Bending Forward to Coil or Uncoil Cable..........................................6-3 Figure 6-4 An Electrician Pulling Cable Over a Pipe ................................................................6-4 Figure 6-5 An Electrician Reaching Over His Shoulders to Secure Cable to a Pipe ................6-4 Figure 6-6 An Electrician Bending to Pull Cable Through a Railing..........................................6-5

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LIST OF TABLES

Table 4-1 Recommended Heights for Location of Electrical Boxes for the General Population in North America and Other Regions of the World.............................................4-2

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CONTENTS 1 INTRODUCTION ....................................................................................................................1-1

Study Objectives ..................................................................................................................1-1 Background..........................................................................................................................1-2

Need for Increased Power Generation...........................................................................1-2 Selection of Worker Groups for the Current Projects .....................................................1-2

Long-Term Goals .................................................................................................................1-3

2 METHODS ..............................................................................................................................2-1 Laboratory Studies ...............................................................................................................2-1 Field Observations from Site Visits ......................................................................................2-1

3 PRELIMINARY RESULTS .....................................................................................................3-1 Site Visits .............................................................................................................................3-1 General Protocol and Procedures........................................................................................3-1 Tasks Evaluated and Recommended Ergonomic Interventions ..........................................3-1

4 LOCATING ELECTRICAL BOXES........................................................................................4-1 Current Work Practice..........................................................................................................4-1 Problems with Current Work Practices ................................................................................4-1 Recommended Ergonomic Intervention...............................................................................4-2 Benefits of Ergonomic Intervention ......................................................................................4-3 Discussion............................................................................................................................4-3

5 CRIMPING CONNECTORS ...................................................................................................5-1 Current Work Practices ........................................................................................................5-1 Problems with Using Manual Presses..................................................................................5-2 Recommended Ergonomic Intervention...............................................................................5-2 Benefits of Using a Battery-Powered Press .........................................................................5-2 Discussion............................................................................................................................5-3

6 INSTALLING AND REMOVING TEMPORARY WIRE AND CABLE.....................................6-1 Current Work Practice..........................................................................................................6-1 Problems with Current Work Practices ................................................................................6-1 Recommended Ergonomic Intervention...............................................................................6-2 Benefits of Ergonomic Interventions ....................................................................................6-2 Discussion............................................................................................................................6-2

7 FUTURE WORK .....................................................................................................................7-1 Laboratory Studies ...............................................................................................................7-1

8 REFERENCES .......................................................................................................................8-1

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1 INTRODUCTION This project, which focuses on improving the occupational health of electricians at fossil-fueled power plants, is an extension of previous projects sponsored by EPRI (EPRI, 2001, 2004 and 2005). In those projects, an ergonomics process was established for overhead distribution line workers and underground workers (manhole/vault and direct buried cable workers) at an upper Midwest electric power utility. The ergonomics team members evaluated common tasks that overhead distribution line and underground workers performed throughout utilities across the U.S. The team generated improvements to these tasks to the reduce risk of musculoskeletal disorders (MSDs), such as low back pain, shoulder tendonitis and bursitis, wrist tenosynovitis and carpal tunnel syndrome. In addition, the team recommended specific ergonomic interventions for these tasks. The culmination of these projects was three EPRI ergonomics handbooks for the electric power industry published by EPRI in Dec. 2001, 2004 and 2005 entitled Overhead Distribution Line Workers Interventions, Ergonomic Interventions for Manhole, Vault and Conduit Applications and Ergonomic Interventions for Direct Buried Cable Applications respectively. These handbooks described ergonomic improvements for 16 to 32 tasks in lay language and simple line drawings. The handbooks have been well received by safety and health professionals and line workers at electric utilities across the U.S. and have spawned interest among several electric utilities to either start an ergonomics process or enhance their existing ergonomics process.

The current project is the first formal research project whose focus is improving the occupational health of electricians who work in fossil-fueled power plants throughout the U.S. In this project, common tasks of electricians will be evaluated in both laboratory and field settings to quantify the occupational health benefits of ergonomic modifications. Laboratory testing will occur at the Industrial Ergonomics Laboratory at Marquette University (Milwaukee, WI), and field testing will be conducted by electricians at the central utility. New tools, equipment, and methods of electrical work will be evaluated for ergonomic and cost feasibility. To ensure applicability of results from this project to electric utilities across the U.S., the work practices evaluated in this project will be selected based on observations of electricians work practices from electric utilities across the U.S.

Study Objectives

1. To quantitatively evaluate electricians tasks that pose medium to high risk of MSDs with biomechanical instruments and software models. Such disorders could include low back pain, shoulder tendonitis and bursitis, carpal tunnel syndrome, and wrist tenosynovitis. Quantitative biomechanical measures will be used to document physical stressor endpoints before and after interventions.

2. To develop an ergonomics process for electricians at the central utility. This includes training in order for the workers to sustain the ergonomics process.

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3. To prepare an ergonomics handbook for electricians that will describe and illustrate in detail those work practices that can be improved by modifications in equipment, tools or methods. The handbook will focus on work practices involving only electricians. This handbook will be available from EPRI December 2007.

Background

Need for Increased Power Generation Demand for electricity in the US is predicted to increase 50% over the next 20 years (at an average rate of 1.8% per year), from 3,657 billion kilowatt-hours that were produced in 2003 to 5,467 billion kilowatt-hours in 2025 (Annual Energy Outlook (AEO), US DOE, 2005, p. 4). A major reason for the increase in consumption of electricity is due to the projected increase in the average size of homes in terms of both square footage and ceiling height, with corresponding increases in use of electricity for heating, cooling and lighting. Another major reason is the expected shift in population to warmer climates, which increases the amount of electricity consumed for air conditioning (AEO, 2005, p. 87) Meeting the increasing demand for electricity till 2025 in the US will require more fossil-fueled electric power plants, in particular natural gas and coal. More than 60% of the new power capacity from electric power plants is projected to be from natural-gas-fired plants. In the later years of the forecasted period (2020 to 2025), coal is projected to be the leading fuel for new capacity of electric power (AEO, 2005, p. 87). Overall, total consumption of coal for producing electric power is expected to increase 42%, from 1,004 million tons in 2003 to 1.425 million tons in 2025 (annual rate increase of 1.6%). Eighty-seven gigawatts of new coal-fired power plants are projected to be constructed between 2004 and 2025 in the US (AEO, 2005, p. 6), which translates into 116 new coal-burning power plants in the next 20 years (assuming one plant produces a peak level of 750 megawatts of electricity). The share of electricity generated from natural gas is expected to increase from 16% in 2003 to 24% in 2025 while the share from coal is expected to remain stable at around 50% (AEO, 2005, p. 6). Thus, natural gas and coal are expected to power approximately 75% of total electricity production by 2025 in the US. The dependence of the US on fossil fuels for electricity is high now (about 66% of total electricity) and is expected to be even greater in the next 20 years. Capacity increases over the next two decades will be necessary due to population and industrial growth.

Selection of Worker Groups for the Current Projects It is vital for fossil-fueled power plants to be productive and efficient to meet growing electricity needs and minimize cost and emissions. Electricians play an important role in keeping fossil-fueled power plants running efficiently and smoothly. The occupational safety and health aspects of the tasks that these workers perform can influence the productivity and efficiency of the power plants as injuries to electricians can prolong planned or emergency outages or lower the quality of the repair work. Thus, it is in the interest of the utilities to design the tasks that electricians perform to minimize risk of injuries. Ergonomics the science of assessing the risk of injury from tasks, generating possible interventions (engineering or administrative), and then evaluating proposed interventions can play a vital role in minimizing the incidence and

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severity of injuries to fossil-fueled power plant workers while often improving the quality of the work.

Many trades are responsible for the smooth, efficient running of fossil-fueled power plants. Electricians are one group that was selected for study in the current project because they are essential to the operation and maintenance of power plants. They were also selected because of their high rate of MSDs, such as sprains/strains (ergonomics addresses these types of injuries.) Based on a seven year study of incidence and severity of injuries in eight electric power utilities, electricians had the second highest percentage of medical claims across all occupational groups within electric utilities (17.0%) (EPRI, 2002, p. 2-17). Furthermore, incidence rate of injuries to electricians was 0.08 (normalized to 100 employee-years), which was the second greatest of all job classifications (EPRI, 2002, p. 2-9). Thus, based on their high incidence, severity and cost rates of injuries related to ergonomics, electricians were chosen for study in the proposed project.

Long-Term Goals The long term goals of this project are the following:

1. Improved occupational health of fossil-fueled power plant electricians. 2. Reduced workers' compensation cost (in constant dollars) of MSDs (not acute trauma). 3. Enhanced quality of work and improved job satisfaction of electricians.

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2 METHODS

Laboratory Studies The first study objective (quantitative testing of work practices in the laboratory) has not been completed, although one study is in progress (evaluation of screwdrivers) and another is in the planning stage (evaluation of cart design for moving heavy loads). The Future Work section has details on how these two studies will be conducted in the Industrial Ergonomics Laboratory at Marquette University.

Field Observations from Site Visits In order to ascertain the broadest scope of tasks involving electrical work, the research team made three site visits to utilities across the United States to observe electricians performing typical tasks. The primary purpose of these site visits was to compile a list of work practices that are common to utilities throughout the U.S. and that may be problematic with respect to MSDs. A secondary purpose was to note regional differences in work practices used to accomplish these tasks across the country.

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3 PRELIMINARY RESULTS

Site Visits From 2005 to 2006, three site visits were conducted at one utility in the U.S. West and two utilities in the U.S. Northeast. Marquette University personnel, fossil operations health and safety consultant from the central utility, and at least two electricians from the central utility visited these electric power utilities for at least two days and observed electricians from the host utilities performing typical electrical tasks.

General Protocol and Procedures The site visit research team documented electrical work practices by video and digital photography and measured weights of materials that were handled and lifted. In addition, dimensions of equipment, parts and tools used by the host utilities were recorded.

Tasks Evaluated and Recommended Ergonomic Interventions Under the direction of personnel from Marquette University, the electricians ergonomics team at the central utility evaluated three tasks with the Task Hazard Evaluation Form (Appendix C of the Overhead Distribution Line Workers Interventions Handbook (EPRI, 2001)). The team then brainstormed possible improvements to the work practices and recommended ergonomic interventions to reduce the risk factors of MSDs. These three tasks and their corresponding recommended ergonomic interventions are described below. The tasks were chosen based on observations made at the central utility and the site visit utilities.

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4 LOCATING ELECTRICAL BOXES

Current Work Practice Power plant electricians install and perform maintenance tasks within electrical boxes in all areas of a power plant. Some examples of these types of enclosures are terminal or lead boxes, disconnect switches, light switches and junction boxes containing communication equipment. Electrical boxes range in size from a small handy box that is approximately 2 in. by 4 in. to a terminal box that can be as large as 4 ft. by 4 ft. Depending on the complexity of the task and the number of electrical boxes, it may take several days to complete these tasks. The frequency of the task varies, but typically could occur once a week for power plant electricians. Typical work items for electrical boxes include the following:

Installing/removing electrical box(es). Open/close the hinged door or remove/replace the cover. Test for voltage or current using a meter. Lift, disconnect and land leads. Pull fuses and remove or install additional conductors. Drill out and knock out holes for new conduit. Problems with Current Work Practices Due to either the original design of the power plant or previous retrofitting, electrical boxes can be located on the floor, near the floor, over the shoulders and in difficult to access spaces. Figures 4-1 and 4-2 show an electrician with awkward, often sustained, body postures while working on electrical boxes that were mounted either on the floor on near floor level. Depending on the height and location of the electrical box, the electrician may be exposed to the following risk factors for back and lower and upper extremity musculoskeletal disorders (MSDs):

1. Sustained (static) extreme forward bending of the trunk (flexion) 2. Trunk twisting (rotation) 3. Sustained above shoulder work (shoulder abduction and flexion) and neck extension 4. Pulling cable with above shoulder posture 5. Sustained kneeling 6. Contact stress to the trunk and upper and lower extremities from obstacles blocking

access to the electrical box

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Recommended Ergonomic Intervention In those tasks where electricians can relocate an electrical box, the electrical box should be located at approximately chest height and in an area free of obstacles and physical restrictions. As illustrated in Figures 4-3 and 4-4, electrical boxes located at the chest height of the worker minimize awkward postures of the trunk and upper and lower extremities. Table 4-1 shows the average chest height of the general population from North America (U.S and Canada) and populations from other regions in the world. The heights shown in Table 4-1 are the recommended heights for electrical boxes for power plants in North America and other regions. Because the difference between the 50th percentile chest height for men and women is minimal, the average of the two is the recommended height for installing electrical boxes.

Table 4-1 Recommended Heights for Location of Electrical Boxes for the General Population in North America and Other Regions of the World

Mens 50th % Womens 50th % Average Region Chest Height

Inches (cm)1 Chest Height Inches (cm)1

Chest Height Inches (cm)1

North America (U.S. & Canada) 53.6 (131) 48.9 (120) 51.3 (126)

Other Population Groups2

Mexico 47.9 (117) 43.2 (106) 45.6 (112) Latin America European & Negroid

52.3 (128) 47.9 (117) 50.1 (123)

Northern Europe 54.3 (133) 50.3 (123) 52.3 (128)

Central Europe 53.0 (130) 49.3 (121) 51.1 (125) Eastern Europe 52.3 (128) 48.3 (118) 50.3 (123) Southeastern Europe 51.6 (126) 47.9 (117) 49.8 (122)

Iberian Peninsula 50.9 (125) 47.3 (116) 49.1 (120)

North Africa 50.3 (123) 47.6 (117) 48.9 (120) West Africa 49.6 (122) 44.9 (110) 47.3 (116) Southeastern Africa 49.9 (122) 46.3 (113) 48.1 (118)

Near East 50.9 (125) 47.6 (117) 49.3 (121) North India 49.6 (122) 45.3 (110) 47.4 (116) South India 47.9 (117) 43.9 (108) 45.9 (113) North Asia 48.3 (123) 46.9 (115) 47.6 (121) South China 49.9 (122) 44.6 (109) 47.3 (116)

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Table 4-1 (continued) Recommended Heights for Location of Electrical Boxes for the General Population in North America and Other Regions of the World

Mens 50th % Womens 50th % Average Region Chest Height

Inches (cm)1 Chest Height Inches (cm)1

Chest Height Inches (cm)1

Other Population Groups2 (continued) Southeast Asia 48.3 (118) 44.9 (110) 46.6 (114) Australia 53.0 (130) 49.6 (122) 51.3 (126) Japan 51.3 (126) 46.9 (115) 49.1 (120)

1Average chest height calculated utilizing the data and the regression equation presented in the forthcoming EPRI Ergonomics Handbook for Electricians. 2Anthropometric data for other population groups were found in a publication from Jurgens, Aune, and Pieper (1990).

Benefits of Ergonomic Intervention Installing electrical boxes at the recommended height in Table 4-1 has the following benefits:

1. Significantly reduces forward trunk bending (flexion) 2. Minimizes trunk twisting (rotation) 3. Reduces above shoulder work (flexion and abduction) and neck extension 4. Eliminates kneeling 5. Minimizes contact stress to the trunk and upper and lower extremities 6. Decreased physical stress to the shoulders, arms and hands from pulling cable with above

shoulder arm posture. The capability to exert forces with the arms and hands above shoulder level is less than if the force were exerted at chest height (Eastman Kodak, 1986, p. 388)

Discussion 1. If the existing electrical box is located in a place that causes awkward postures or contact

stresses, then electricians should consider moving the box to a location at the recommended height and free of obstacles and physical restraints.

2. Before relocating the electrical box, the electrician should determine the desired location and assess the area to identify the proper mounting material (e.g. channel unistruts, threaded rods and hangers, etc.).

3. An electrician may also want to illuminate the work area with a hands-free light source, such as a helmet-mounted flashlight. Illuminating the work area in this way makes the work safer and enables the electrician to work with both hands.

4. In order to reach high electrical boxes, some workers may need to stand on an object, which may not provide a stable surface for standing. Precarious footing may expose workers to slips, falls, and possibly electrical hazards.

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Figure 4-1 An Electrician Kneeling to Work on an Electrical Box Located at Floor Level

Figure 4-2 An Electrician Kneeling to Work on an Electrical Box Located at Floor Level

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Figure 4-3 An Electrician Working on an Electrical Box at an Appropriate Height

Figure 4-4 An Electrician Working on an Electrical Box at an Appropriate Height

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5 CRIMPING CONNECTORS

Current Work Practices The purpose of connectors is to join two wires or cables together and to finish a termination. There are many types of connectors used by electricians in power plants; examples of connectors are crimp lugs and butt splices. Electricians crimp connectors at various locations throughout power plants. Crimping connectors on wire and cable smaller than 10 AWG can normally be performed with a hand crimper with short to medium length handles as shown in Figure 5-1. For crimping connectors on cable larger than 10 AWG and smaller than 3/0 AWG, a long-handled manual press may be used as shown in Figure 5-2. For crimping connectors on cable 3/0 AWG or larger, an electrician may use a pump-actuated manual press (Figure 5-3) or an AC-powered pump with a hydraulic press (Figure 5-4). A long-handled manual press weighs approximately 22 lbs. and has handles that are approximately 14 to 16 in. long (Figure 5-2). It is commonly used for crimping connectors on cable and wire up to 3/0 AWG. When the handles are completely open, the span between the ends of the handles is approximately 25 in. Figure 5-5 illustrates an electrician using a long-handled manual press.

A pump-actuated manual press weighs 13.5 lbs. and is 23 in. long. It is commonly used for crimping connectors on 3/0 AWG or larger wire and cable. A pump-actuated manual press (Figure 5-3) requires 10 to 20 squeezes of the handles to make one individual crimp, whereas a long-handled manual press can make one individual crimp with one closing of the handles. However, the force required for most of the handle closures with the pump-actuated manual press is less than the force required to crimp with a manual press. The last few handle closures of the pump-actuated press require more force than the earlier closures.

A hydraulic press may also be powered by a battery pack, gasoline engine or AC motor (Figure 5-4). The pump and head have a combined weight ranging from 26 to 44 lbs. The press head is connected to the pump via a hydraulic hose, and a switch is activated to close the jaws of the press around the connector. A hydraulic press with a pump is commonly used to crimp connectors on 3/0 AWG or larger conductors.

Power plant electricians may crimp connectors on a daily basis; the number of crimps per day ranges from 10 to several hundred. For wire 10 AWG and smaller, only one crimp per wire is required. However, for larger wire, more than one crimp is often required.

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Problems with Using Manual Presses Using a long-handled manual press or a pump-actuated manual press has the following risk factors for spine, shoulder, elbow, forearm and wrist musculoskeletal disorders (MSDs):

1. Shoulder elevation (flexion) and reaching out to the side (abduction) to open the handles of the long-handled manual press. Depending on the location where the crimp needs to be made, the arms may be raised above the shoulder or head while exerting a high force.

2. The shoulder, arm and hand muscles exert high forces to close the handles of the long handled manual press. High forces are also required to perform the last few closures of the handles of the pump-actuated manual press.

3. Twisting of the neck and trunk twisting to perform a crimp. In some locations, an electrician may lie on his or her stomach or back to make the connection.

4. Forearm twisting (pronation and supination) to rotate the pump-actuated manual press prior to crimping a connector.

5. Depending on the cable orientation, repetitive shoulder and arm exertions to push and pull the handles on the pump-actuated manual press.

Recommended Ergonomic Intervention As shown in Figures 5-7 and 5-8, a battery-powered press is the preferred ergonomic intervention for crimping connectors on wire and cable larger than 3/0 AWG. A typical battery-powered press for crimping connectors on 3/0 AWG or larger conductors weighs approximately 10 to 15 lbs. and is about 13 in. long. In the same manner as a manual press, the jaws of a battery-powered press open and fit over the connector. A trigger on the battery-powered press is depressed and held until the connector is fully crimped. The battery-powered press will stop crimping when the required crimping force is achieved. The process is repeated until the required number of crimps is made on a connector.

If a battery-powered press is not available, then a pump with a hydraulic press is recommended for crimping connectors.

Benefits of Using a Battery-Powered Press

1. Reduces shoulder elevation (flexion) and reaching out to the side (abduction). 2. Substantially reduces shoulder force exertions. 3. Reduces neck and trunk twisting, particularly when an electrician is kneeling or lying on

the ground and reaching into an area with limited space to crimp. 4. Eliminates forearm twisting (pronation and supination) to rotate the handle on the pump-

actuated manual press. 5. Eliminates repetitive pushing and pulling on the handles of the pump-actuated manual

press. 6. While working in confined area, a battery-powered press does not require the space to be

as large as that required when using a manual press. Therefore, there is not the extra physical effort associated with working in a confined area such as when removing and replacing a junction box or cover.

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Discussion 1. Commercially available battery-powered presses vary in crimping speed under load. Two

important factors that utilities should consider when making decisions on which battery-powered press to purchase are the speed and quality of a crimp under load.

2. Compared to a hydraulic press with a pump, a battery-powered press is more compact, lighter in weight and has shorter set-up time. The need for an external power source and use of hoses may also limit the job sites where a hydraulic press with a pump can be used.

3. Compared to a hydraulic press with a pump, less physical effort is required to transport a battery-powered press from the maintenance area to the job site. Greater physical effort and possibly awkward body postures are required for the following:

Lifting and carrying the components of the hydraulic press and pump from the maintenance area to the job site.

Setting up the external power source (AC, battery, or gasoline). Proper positioning of hoses that may be cumbersome and heavy.

4. Safe operation of a hydraulic press with a pump requires two electricians: one to hold the press and one to operate the pump unit. However, only one electrician is needed to operate a battery-powered press.

5. Battery-powered presses are typically designed to be held in a more balanced position as compared to the head and hose of a pump with a hydraulic press.

6. While a battery-powered press weighs more than a long-handled manual press (10 to 15 lbs. vs. approximately 8 lbs.), some of the weight of the battery-powered press can be supported by the cable while crimping a connection. Therefore, the forces exerted by the arm and shoulder muscles that are required to hold the battery-powered press during crimping are reduced.

7. Although a battery-powered press initially costs substantially more than a long-handled manual press, a battery-powered press significantly reduces the exposure to risk factors of MSDs and may be more cost effective in the long term. Chapter 4 in the EPRI Ergonomics Handbook for the Electric Power Industry: Overhead Distribution Line Workers Interventions (Dec. 2001, EPRI document #1005199) showed that for overhead distribution applications, the payback period for purchasing the more expensive battery-powered press compared to the manual press was less than 12 months. Chapter 4 EPRI Ergonomics Handbook for the Electric Power Industry: Ergonomic Interventions for Direct-buried Cable Applications (March 2005, EPRI document #1005574) addressed the payback period for purchasing battery-powered presses for underground applications. Based on an extensive analysis of the cost of workers compensation, medical expenses, and training of new workers over a 30-year period at a medium-sized electric utility in the U.S., the payback period for replacing a manual press with a battery-powered press was 15 months. In the upcoming EPRI Ergonomics Handbook for electricians, there will be a chapter addressing the payback period for the purchase of battery-powered tools for power plant electricians.

8. There are some commercially available battery-powered presses that can accommodate all of the dies that are used by the manual press as well as the pump-actuated manual press.

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Figure 5-1 Hand Crimper

Figure 5-2 Long-Handled Manual Press

Figure 5-3 Pump-Actuated Manual Press

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Figure 5-4 AC-Powered Pump with Hydraulic Press

Figure 5-5 Crimping a Connector Using a Long-Handled Manual Press

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Figure 5-6 Crimping a Connector Using a Pump-Actuated Press

Figure 5-7 Examples of Battery-Powered Presses for Crimping 3/0 AWG or Larger

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Figure 5-8 Crimping a Connector Using a Battery-Powered Press

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6 INSTALLING AND REMOVING TEMPORARY WIRE AND CABLE

Current Work Practice Power plant electricians install and remove temporary wiring throughout power plants for outages and other special situations that require a power source. These outages and special situations may occur several times per year and require several temporary services each. It may take two or three electricians several days to several weeks to install and remove temporary wiring depending on the extent of the electrical services required.

Installing temporary wiring involves retrieving the wire or cable from the storage area and moving it to the area where the wiring is needed; one or two electricians lift a coil of cable that can weigh up to 225 lbs to and from a pallet or cart as shown in Figures 6-1 and 6-2. An electrician may use a pallet jack to move the cable reel to the area where the cable is needed. The electricians coil and uncoil it (Figure 6-3) and guide it over beams, railings, pipes and/or other structures (Figures 6-4, 6-5, and 6-6). Finally, the electricians terminate both ends of the cable or wire. Removing the temporary wiring is the reverse procedure.

Problems with Current Work Practices Installing and removing temporary wiring exposes electricians to the following risk factors for back and lower and upper extremity musculoskeletal disorders (MSDs):

1. Extreme forward bending of the trunk (flexion) to uncoil and coil the wire or cable. 2. Kneeling on grating or other hard, rough surfaces to tie and untie the coil of cable and

guide the cable in low areas. 3. Lifting coils of cable and wire that weigh up to 225 lbs. 4. Sustained above shoulder work (shoulder abduction and flexion), neck extension and

forward trunk bending (flexion) to guide the cable over beams, railings, pipes and other structures.

5. Forearm twisting (pronation and supination) to connect and disconnect the wire and cable to and from a power source or load.

6. Forceful pulling to coil, uncoil and guide the wire and cable.

6-2

Recommended Ergonomic Intervention In areas where temporary wiring is frequently needed, it is recommended that permanent wiring be installed. In areas where temporary wiring is not as frequently required and areas where it may not be feasible to install permanent wiring, then it is recommended that the wiring be stored in convenient locations. If possible, store wire and cable on a reel to reduce the pulling force to coil and uncoil it.

Benefits of Ergonomic Interventions Installing permanent wiring eliminates all of the risk factors listed in the section Problems with Current Work Practice. Storing wire and cable in a convenient location minimizes lifting and lowering force and use of a reel may reduce the pulling force to coil and uncoil the wire and cable.

Discussion

1. Storing wire and cable in a location that is convenient to the area where the wire and cable will be installed reduces the preparation time for installation.

2. The initial cost to install permanent wire and cable may be high.. However, this cost would have a short payback period by eliminating the need for electricians to repeatedly install and remove temporary wiring.

Figure 6-1 An Electrician Lifting a Coil of Cable from a Cart

6-3

Figure 6-2 Coils of Cable on a Pallet

Figure 6-3 An Electrician Bending Forward to Coil or Uncoil Cable

6-4

Figure 6-4 An Electrician Pulling Cable Over a Pipe

Figure 6-5 An Electrician Reaching Over His Shoulders to Secure Cable to a Pipe

6-5

Figure 6-6 An Electrician Bending to Pull Cable Through a Railing

7-1

7 FUTURE WORK

Laboratory Studies Two tasks will be evaluated quantitatively in the Industrial Ergonomics Laboratory at Marquette University. The first study, which is in progress, involves design of screwdrivers; screwdrivers are the tools that electricians use most commonly. The shape of the handle (in-line vs. bent) is being evaluated in terms of torque and comfort, and a ratchet mechanism will be evaluated in terms of performance (time required to insert or remove screw) and comfort. The second laboratory study will be an evaluation of the effect of cart design on the push and pull forces required to move heavy objects, such as 750 lbs. motors. The conventional 4-wheel (2 swivel and 2 fixed) configuration will be compared to an alternate 6-wheel design (4 swivel wheels at the corners and 2 fixed in the middle). In both laboratory studies, major skeletal muscles of subjects will be monitored with electromyography (EMG) to assess the muscle force required to perform tasks. The Biometrics DATALINK systems will be used to record electrical activity from surface surface electrodes attached to skin. A large percentage of the subjects will be electricians from the central utility who are free of injury and in reasonably good health. Expected number of subjects for each of the two studies is 15 or more.

An ergonomics handbook for electricians in fossil-fueled power plants will be written and illustrated in the same format as the Overhead Distribution Line Workers Interventions Handbook (EPRI, 2001), Ergonomic Interventions for Manhole, Vault and Conduit Applications (EPRI, 2004) and Ergonomic Interventions for Direct-Buried Cable Applications (EPRI, 2005). Approximately 16 electrical tasks and their corresponding ergonomic interventions will be described in lay language and illustrated with simple line drawings. The three tasks in this progress report represent the writing and illustration style of the tasks that will be included in the handbook. Appendices that show results from the two laboratory studies will be included in the final handbook.

8-1

8 REFERENCES Eastman Kodak. Ergonomic Design for People at Work, Volume 2. Van Nostrand Reinhold:1986.

EPRI. EPRI Ergonomics Handbook for the Electric Power Industry: Overhead Distribution Line Workers Interventions, EPRI, Palo Alto, CA: 2001. 1005199.

EPRI. Occupational Health and Safety Annual Report 2002: Injury and Illness Trends in the Electric Energy Workforce, 1995-2001, EPRI, Palo Alto, CA: 2002. 1005425. EPRI. EPRI Ergonomics Handbook for the Electric Power Industry: Ergonomic Interventions for Manhole, Vault and Conduit Applications. EPRI, Palo Alto, CA: 2004. 1005430. EPRI. EPRI Ergonomics Handbook for the Electric Power Industry: Ergonomic Interventions for Direct-Buried Cable Applications. EPRI, Palo Alto, CA: 2005. 1005574. Jurgens, H., Aune, I. and Pieper U. International Data on Anthropometry. International Labour Office, Geneva. 1990.

Marklin, R.W., Wilzbacher, J., and Lazuardi, L. Measurement of handle forces for crimping connectors and cutting cable in the electric power industry. International Journal of Industrial Ergonomics: 2004, 34, 497-506.

Pheasant, S. BodySpace: Anthropometry, Ergonomics and the Design of Work. Taylor and Francis, 1996.

Stone, A., Usher, D., Marklin, R., Seeley, P. and Yager, J. Case study for underground workers at an electric utility: How a research institution, university and industry collaboration improved occupational health through ergonomics. Journal of Occupational and Environmental Hygiene: 2006, 3: 397-407.

US DOE. Annual Energy Outlook 2005 with Projections to 2025. Energy Information Administration, Office of Integrated Analysis and Forecasting, US Department of Energy (US DOE). Washington DC: 2005. www.eia.doe.gov/oiaf/aeo/

ELECTRIC POWER RESEARCH INSTITUTE 3420 Hillview Avenue, Palo Alto, California 94304-1338 PO Box 10412, Palo Alto, California 94303-0813 USA

800.313.3774 650.855.2121 askepri@epri.com www.epri.com

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The Electric Power Research Institute (EPRI) The Electric Power Research Institute (EPRI), with major locations in Palo Alto, California, and Charlotte, North Carolina, was established in 1973 as an independent, nonprofit center for public interest energy and environmental research. EPRI brings together members, participants, the Institutes scientists and engineers, and other leading experts to work collaboratively on solutions to the challenges of electric power. These solutions span nearly every area of electricity generation, delivery, and use, including health, safety, and environment. EPRIs members represent over 90% of the electricity generated in the United States. International participation represents nearly 15% of EPRIs total research, development, and demonstration program.

TogetherShaping the Future of Electricity

2006 Electric Power Research Institute (EPRI), Inc. All rights reserved. Electric Power Research Institute and EPRI are registered service marks of the Electric Power Research Institute, Inc.

Printed on recycled paper in the United States of America 1012570

1 INTRODUCTIONStudy ObjectivesBackground Need for Increased Power GenerationSelection of Worker Groups for the Current Projects

Long-Term Goals

2 METHODSLaboratory StudiesField Observations from Site Visits

3 PRELIMINARY RESULTS Site VisitsGeneral Protocol and ProceduresTasks Evaluated and Recommended Ergonomic Interventions

4 LOCATING ELECTRICAL BOXESCurrent Work Practice Problems with Current Work PracticesRecommended Ergonomic InterventionBenefits of Ergonomic InterventionDiscussion

5 CRIMPING CONNECTORSCurrent Work Practices Problems with Using Manual Presses Recommended Ergonomic InterventionBenefits of Using a Battery-Powered PressDiscussion

6 INSTALLING AND REMOVING TEMPORARY WIRE AND CABLECurrent Work Practice Problems with Current Work PracticesRecommended Ergonomic InterventionBenefits of Ergonomic InterventionsDiscussion

7 FUTURE WORKLaboratory Studies

8 REFERENCES

Text1: Effective December 6, 2006, this report has been made publicly available in accordance with Section 734.3(b)(3) and published in accordance with Section 734.7 of the U.S. Export Administration Regulations. As a result of this publication, this report is subject to only copyright protection and does not require any license agreement from EPRI. This notice supersedes the export control restrictions and any proprietary licensed material notices embedded in the document prior to publication.