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Ergonomics eTool: Solutions for Electrical Contractors
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Lifting heavy items is one of the leading causes of injury in the workplace. In 2001, the Bureau of Labor Statistics reported that over 36 percent of injuries involving missed workdays were the result of shoulder and back injuries. Overexertion and cumulative trauma were the biggest factors in these injuries.

When employees use smart lifting practices and work in their "power zone," they are less likely to suffer from back sprains, muscle pulls, wrist injuries, elbow injuries, spinal injuries, and other injuries caused by lifting heavy objects.


Employee bent over lifting
 

Weight of Objects
Potential Hazards:
 
  • Some loads, such as large spools of wire (Figure 1), bundles of conduit, or heavy tools and machinery place great stress on muscles, discs, and vertebrae.

  • Lifting loads heavier than about 50 pounds will increase the risk of injury.

Possible Solutions:
  • Use mechanical means such as forklifts (Figure 2) or duct lifts to lift heavy spools, transformers, switch gear, service sections, conduit, and machinery.

  • Use pallet jacks and hand trucks to transport heavy items.

  • Avoid rolling spools. Once they are in motion, it is difficult to stop them.

  • Use suction devices (Figure 3) to lift junction boxes and other materials with smooth, flat surfaces. These tools place a temporary handle that makes lifting easier.
     
  • Use ramps or lift gates to load machinery into trucks rather than lifting it.
     
  • Materials that must be manually lifted should be placed at "power zone" height, about mid-thigh to mid-chest. Special care should be taken to ensure proper lifting principles are used. Maintain neutral and straight spine alignment whenever possible. Usually, bending at the knees, not the waist, helps maintain proper spine alignment.
     
  • Place materials that are to be manually lifted at "power zone" height, about mid-thigh to mid-chest. Maintain neutral and straight spine alignment whenever possible. Usually, bending at the knees, not the waist, helps maintain proper spine alignment.
     
  • Order supplies in smaller quantities and break down loads off-site. When possible, request that vendors and suppliers break down loads prior to delivery.
Figure 1. A spool holding 117 pounds of wire
Figure 1.
A spool holding 117 pounds of wire.

Figure 2. Forklift
Figure 2.
Forklift.

Figure 3. Suction tool
Figure 3.
Suction tool.
 
Figure 4. Two-man lift
Figure 4.
Two-man lift.
  • Prefabricate items in a central area where mechanical lifts can be used. Only transport smaller, finished products to the site.

  • Limit weight you lift to no more than 50 pounds. When lifting loads heavier than 50 pounds, use two or more people to lift the load (Figure 4).

  • Work with suppliers to make smaller, lighter containers.


Awkward Postures
Potential Hazards:
 
  • Bending while lifting (Figure 5) forces the back to support the weight of the upper body in addition to the weight you are lifting. Bending while lifting places strain on the back even when lifting something as light as a screwdriver.

  • Bending moves the load away from the body and allows leverage to significantly increase the effective load on the back. This increases the stress on the lower spine and fatigues the muscles.

  • Reaching moves the load away from the back, increases the effective load, and places considerable strain on the shoulders.

  • Carrying loads on one shoulder, under an arm, or in one hand, creates uneven pressure on the spine.

  • Poor housekeeping limits proper access to objects being lifted, and forces awkward postures.
Figure 5. Employee twisting in an awkward position.
Figure 5.
Employee twisting in
an awkward position.
Possible Solutions:
 
  • Move items close to your body and use your legs when lifting an item from a low location (Figure 6).

  • Store and place materials that need to be manually lifted and transported at "power zone" height, about mid-thigh to mid-chest.

  • Minimize bending and reaching by placing heavy objects on shelves, tables, or racks. For example, stack spools on pallets to raise them into the power zone.

  • Avoid twisting, especially when bending forward while lifting. Turn by moving the feet rather than twisting the torso.

  • Keep your elbows close to your body and keep the load as close to your body as possible.
     
  • Keep the vertical distance of lifts between mid-thigh and shoulder height. Do not start a lift below mid-thigh height nor end the lift above shoulder height. Lifting from below waist height puts stress on legs, knees, and back. Lifting above shoulder height puts stress on the upper back, shoulders, and arms.
Figure 6. Employee lifting a box
Figure 6.
Different approaches
to lifting.
Figure 7. Aerial lift
Figure 7.
Aerial lift.
  • Use ladders or aerial lifts (Figure 7) to elevate employees and move them closer to the work area so overhead reaching is minimized.

  • Break down loads into smaller units and carry one in each hand to equalize loads. Use buckets with handles, or similar devices, to carry loose items.

  • Keep the load close to the body. When lifting large, bulky loads, it may be better to bend at the waist instead of at the knees in order to keep the load closer to your body.

  • Optimize employee access to heavy items through good housekeeping and preplanning.

  • Use roll-out decks installed in truck beds to bring materials closer to the employee and eliminate the need to crawl into the back of a truck. See the Vehicular Activities section for more information.


High-Frequency and Long-Duration Lifting
Potential Hazards:
 
  • Holding items for a long period of time, such as when installing fixtures or j-boxes (Figure 8), even if loads are light, increases risk of back and shoulder injury, since muscles can be starved of nutrients and waste products can build up.

  • Repeatedly exerting, such as when pulling wire, can fatigue muscles by limiting recuperation times. Inadequate rest periods do not allow the body to rest.
Figure 8. Employee reaching overhead
Figure 8.
Employee reaching
overhead.
Possible Solutions:
 
  • Use a template made of a lightweight material (Figure 9) such as cardboard to mark holes for drilling when mounting heavy items such as junction boxes and service panels. This ensures that the heavier item does not need to be held in place to level and measure for anchor mounts.

  • Provide stands, jigs, or mechanical lifting devices such as duct lifts to hold large, awkward materials such as junction boxes and service panels in place for fastening.

  • Rotate tasks so employees are not exposed to the same activity for too long.

  • Work in teams; one employee lifts and holds items while the other assembles.

  • Take regular breaks and break tasks into shorter segments. This will give muscles adequate time to rest. Working through breaks increases the risk of musculoskeletal disorders (MSDs), accidents, and reduces the quality of work because employees are overfatigued.
Figure 9. Cardboard template for lighting fixtures
Figure 9.
Cardboard template for lighting fixtures.
 
Figure 10. A prefabricated electrical box
Figure 10.
A prefabricated electrical box.
  • Plan work activities so employees can limit the time they spend holding loads.

  • Pre-assemble work items such as fixtures or boxes (Figure 10) to minimize the time employees spend handling them.


Inadequate Handholds
Potential Hazards:
 
  • Inadequate handholds (Figure 11) make lifting more difficult, move the load away from the body, lower lift heights, and increase the risk of contact stress and of dropping the load.
Figure 11. Boxes without handles
Figure 11.
Boxes without handles.
Possible Solutions:
 
  • Utilize proper handholds, including handles, slots, or holes (Figure 12), with enough room to accommodate gloved hands.

  • Ask suppliers to place their materials in containers with proper handholds.

  • Move materials from containers with poor handholds or without handholds into containers with good handholds.

  • Wear proper personal protective equipment (PPE) to avoid finger injuries and contact stress. Ensure that gloves fit properly and provide adequate grip to reduce the chance of dropping the load.

  • Use suction devices (Figure 13) to lift junction boxes and other materials with smooth, flat surfaces. These tools place a temporary handle that makes lifting easier.
Figure 12. Slots in boxes help in lifting
Figure 12.
Slots in boxes help in lifting.
 
Figure 13. Suction device Figure 13.
Suction device.


Environmental Factors
Potential Hazards:
 
  • Cold temperatures can cause decreased muscle flexibility, which can result in muscle pulls.

  • Excessively hot temperatures can lead to dehydration, fatigue, and increased metabolic load.

  • Low visibility or poor lighting (Figure 14) increases the chance of trips and falls.
Figure 14. Work space with window as only light sourceFigure 14.
Work space with window as only light source.
Possible Solutions:
 
 
  • Adjust work schedules to minimize exposure to extreme temperatures.

  • Wear warm clothing when exposed to cold temperatures.

  • Drink lots of water to avoid dehydration in excessive heat.

  • Provide proper lighting (Figure 15) for areas with low light and perform work during daylight hours.

 
Figure 15. Light stand illuminating the work area Figure 15.
Light stand illuminating the work area.

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