Toolbox Safety Topics

Dangers of Powerline Contact

Each year, workers are killed by electrocution from contact with overhead power lines. Over 90 percent of the contacts involved overhead distribution lines. These are the same lines that run in front of our houses and through our job sites. Since they are so common to us, they seem harmless. This serious mistake is fueled by two common misconceptions: the belief that some overhead lines don't carry enough power to kill, and the belief that power lines are well-insulated. Both are dead wrong.

The leading category of contact involves heavy equipment--cranes, drilling rigs, concrete pumps, aerial buckets, and backhoes. Of all heavy equipment contacts, cranes--either mobile or boom trucks--account for 57 percent of electrocutions.

The type of crane most likely to kill the operator is the boom-truck. Contact typically occurs with the rig's boom or load line. Boom trucks are designed with the controls located on the side of the truck chassis, or in some cases attached to a tether. With both designs the operator is in direct contact with the ground. When contact occurs between the equipment and the power line, the electricity looks for the shortest distance to ground. The operator is almost always in this path, and is electrocuted.
But when a mobile crane contacts a power line, it is usually the rigger or ground worker who is electrocuted. Unlike the operator sitting in the cab, they are not isolated from the ground. If a contact occurs while the rigger is attaching a load, or guiding it with a tag line, electricity passes through the load line to the worker on the ground.

Drilling rigs, aerial buckets, backhoes, concrete pumps, and other high-reaching equipment account for another 29 percent of power line contacts. Fatalities associated with high-reach aerial baskets usually occur when the basket makes direct contact with the power line. Accidents involving drilling rigs, however, usually affect the ground workers. With most equipment, the largest number of contacts happen during machinery movement, and not during the setup or take-down phase. The exception is concrete pumps, when incidents tend to occur during the take-down phase. Apparently, during setup and use of the pump operators are more careful. But when the work is completed, they use less caution retracting and storing the boom.

The use of metal extension ladders around power lines is also a frequent cause of fatalities. One study on ladder electrocutions found that virtually all fatalities involved metal ladders. Ladder contacts usually occur during erection, lowering or relocation of the ladder.

Protect yourself from live power lines; look around your work area and identify the location of all power lines before you move or erect any equipment. Make certain that no part of any equipment can come within a minimum of 10 feet from the power line. And remember, this distance is greater for voltages above 50kV. Don't operate equipment around overhead lines unless you are authorized and trained to do so. Contrary to what many people think, overhead power lines do carry enough voltage to kill and most are not insulated.




Heat Stress at Work

HEAT STRESS AND WORKING IN HOT TEMPERATURES


The effects of heat stress range from simple discomfort to life threatening illness such as heat stroke.

What causes heat stress?
It may occur as result of a heat wave or constant source of heat at the workplace. Six main factors involved are temperature, humidity, and movement of air, radiant temperature of surroundings, person’s clothing and physical activity. Working in high temperatures can cause heat stress when more heat is absorbed by the body than can be released through the skin.

Warning signs of heat stress include:
  • Increased sweating causing depletion of the body fluid and causing heat intolerance.
  • Rapid pulse
  • Light-headedness or feeling dizzy, fainting
  • Nausea slurred speech vomiting
  • Fatigue weakness muscular cramps
  • Loss of concentration

    These factors could increase the risk of you having an accident.

    How to avoid heat stress?
  • Drink more fluids (water) frequently to replace fluid.
  • Drinking 100 – 200 ml of water at frequent intervals will be adequate to reduce fluid loss in sweating;
  • Have rest pauses in a cool place
  • Wearing suitable work clothing
    - loose clothing of natural fabric (where clothing is not a safety hazard)
    - Wide brim hats to protect from direct sunlight
  • Use sunscreen creams and adequate instructions.

  • Maintain a healthy life style.

    How should heat stress be treated?
  • Take the person/ sufferer to a cooler place to rest (Eg. building or vehicle)
  • Loosen tight clothing, remove hats or boots if required
  • Give person water to drink – sip small amounts
  • Use a wet sponge or cloth (cold compress) to cool them down

    If the person has painful muscular cramps, a quick source of salt replacement is to add a teaspoon of common salt to 1 litre of water for the person to drink. (Salt tablets should not be taken).

    Contact a first aid officer and your manager if the person does not improve.

    If heat stroke is suspected (person stopped sweating, high body temperature, hot and dry skin, loss of consciousness) medical attention is required urgently! Until medical aid is available, cool the person by soaking the person’s clothing in cold water, giving fluid (if conscious) and fanning the person to increase air movement.

    Report incidents to your Manager and to the Safety Manager/ Safety Co-ordinator.






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    Toolbox Topics Safety Articles

  • Dangers Of Powerline Contact
  • Heat Stress at Work
  • Personal Protective Equipment(PPE)
  • Hazard Identification & Reporting
  • Workplace Slips & Falls
  • Safety & Manual Handling
  • Safety Housekeeping Practice

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