Portable Electric Tools

Each year many workers on construction sites suffer electric shock using portable electrical tools and equipment. The nature of the injuries, including those caused by ground faults, ranges from minor injuries to serious secondary injuries. A secondary injury occurs when a worker recoils from an electric shock and, as a result, sustains an injury. Depending on the surrounding conditions, such an accident can result in a bruise, a broken bone or a fatal fall.

Methods of protection

One method of protection against injury caused by an electrical fault is the use of an equipment grounding conductor commonly known as the third – or green – wire. This equipment grounding conductor grounds the exposed, noncurrent-carrying metal parts of tools or equipment and carries off the leakage and fault currents, thus limiting the voltage on the tool frame by providing a low resistance path to ground.

Another method of protection is the utilization of a ground-fault circuit interrupter (GFCI). GFCI protection is required for ALL jobsite electrical outlets, including outlets at existing homes and businesses. This device continually monitors the current and conductors. If the leakage current to ground (either through the equipment- grounding conductor or through a person) exceeds the trip level, the circuit is interrupted quickly enough to prevent electrocution.

Tips to remember

  • Before using any portable electrical power tool, inspect the plug, cord, on-off switch and housing. Look for cracked, broken or frayed insulation, exposed wires or connections and any evidence of damage in general.
  • Properly tag damaged tools and turn in for repairs. Do not use.
  • Inspect extension cords and the GFCI protected outlets you plug into. Look for evidence of damage and exposed conductors.
  • Check the outlet, extension cord, tool and work area to determine if they are clean and dry.
  • Ensure grinders, saws and similar equipment are provided with appropriate safety guards.
  • Ensure power tools are used with the correct shield, guard or attachment.
  • Ensure all cord-connected, electrically operated equipment is effectively grounded or of the approved double insulated type.
  • Ensure effective guards are over belts, pulleys, chains, sprockets, pinch points and points of operation.
  • Ensure ground-fault circuit interrupters are provided on all temporary electrical 15 and 20 ampere circuits.
  • Check pneumatic and hydraulic hoses on power-operated tools for deterioration.
  • Ensure the work rest is adjusted to within 1/8 inch to the wheel and the tongue is adjusted to within 1/4 inch to the wheel on abrasive wheel grinders.
  • Ensure side guards cover the spindle, nut, flange and 75 percent of the wheel diameter on abrasive wheel grinders.
  • Ensure the maximum RPM rating of each abrasive wheel is compatible with the RPM rating of the grinder motor.
  • Ensure new abrasive wheels are visually inspected and ring-tested before use.
  • Ensure appropriate safety glasses, face shields, etc. are used while using hand or powered tools or equipment that might produce flying materials or is subject to breakage.

Discussion Questions

  • Have you noticed any of our tools that appear to be defective?
  • Do you know why GFCI protection is important on the jobsite?
  • Do you always use the right tool for the job, even if the job takes only a few seconds?