Tom Joyce
Midstate Education and Service Foundation (formerly: Midstate Central Labor Council, AFL-CIO)

The metal casing of power tools can carry an electric current. If there is something wrong with the tool, a fault in the electrical system, or if the circuit is overloaded, a short can carry the current to the person holding the tool. The following safeguards will protect you (in addition to avoiding the shortcuts listed in the section on temporary power).

• Make sure your tool has a 3-wire cord. (Double-insulated tools don't need a ground.)
• If your power tool buzzes, have an electrician check it before you use it again. The tool or the wiring to it may be defective.
• Don't touch an electric tool if it is wet or if you're wet, if you are sweating (towel off periodically), or if you are standing on a wet surface. Wet surfaces are better conductors of electricity than dry surfaces. To give a brief example, if your skin is dry, contact with 120 volts (say through a short in the circuit somewhere to your tool) will send 1 milliamp through your body, a barely perceptible level of current. If it's wet, however, the level of current increases over a hundredfold, to 120 milliamps, enough to cause ventricular fibrillation.
• Safer Tools: Double insulated tools typically have all plastic housing and don't have a third wire for grounding. They protect you from possible shock. Battery-powered tools eliminate the possibility of a shock.
• Always use a GFCI when working where a short is possible (outdoors, moisture present, metal contact is likely).
• Beware of overloading old under-protected electrical service by using high amp electrical equipment (such as floor sanders, heat guns, heaters, blowers, etc.). This can happen in older homes which have inadequate wiring (or homeowner rigged wiring). Check out the system before running heavy duty equipment on a service.
  

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