Housing...Inside and Out

December 4, 1998
Avoid Shocking Experiences

Electric tools, mixers or other appliances may generate electrical shocks to their users under some circumstances.

For a shock to occur there must be a defect in the tool itself. Because of this defect, the electric current can make the metal frame of the tool alive with electricity. The person using the defective tool must also be in contact with the ground. Since electricity is always trying to flow to the ground, the uncontrolled electric current on the metal frame of the appliance will flow through the user's body to the ground.

An individual does not necessarily have to be in direct contact with the ground or the earth. If his or her body touches a water pipe, the metal part of the heating system or any other metal object that makes contact with the ground, the stray current will flow through the individual, to the metal to the ground.

A shock may be fatal when the user of defective electrical equipment makes contact with a second piece of faulty electrical equipment. For example, if a person is using a defective vacuum cleaner and touched the metal standard of a defective floor lamp, the individual's body becomes the pathway for the stray current between these two pieces of defective equipment.

The following precautions will protect you from electrical shock when using electrical tools and equipment:

  • Replace frayed electrical cords or worn insulation that exposes conductors.
  • Replace broken or cracked plugs on appliance, lamp or extension cords. 
  • Repair defective electrical equipment (recognized by a slight tingly shock) at once. Do not delay. The next shock may be fatal. 
  • Purchase only electrical appliances that have been approved by Underwriter Laboratories. These appliances have UL stamped on the attached nameplate or tag. 
  • Ground electrical equipment, electrical tools and appliances. You never know when an electrical tool or an appliance may become defective.

Most new electrical tools and equipment now use a three-conductor cord. If a defect develops and the appliance is connected to a three-wire, 120-volt electrical circuit, the stray current will travel through the third wire rather than the user's body because this wire is the path of least resistance to the earth.


Written by Dr. Francis Graham (Retired)

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