Extension cords are designed to be conveniences, not hazards. But too often the people who use them convert them into hazards. Let us go over some of the ways these safety hazards are formed.

Extension cords are often placed in areas where people aren’t used to having them around, and a tripping hazard results. This type of hazard is one of the more common ones; so, when you use an extension cord, try to keep it out of aisles and other places where pedestrians might trip over it. When someone trips over a cord, there is not only a chance of injury but the plug may be jerked to the extent that it’s damaged, making it an electrical hazard.

Selecting the right extension cord for the job can eliminate many hazards to start with. All cords should be UL listed, properly grounded, and meet other applicable electrical code specifications. If you’re using portable electrical equipment, the equipment should be properly grounded.

Extension cords are items that get considerable usage. Appropriate cords should be used with portable electric tools.
If moisture, heat, or chemicals are present, be sure your cord is the proper type to resist the conditions there. A word of caution, if you make a good connection with a live wire carrying even 110 volts, it can be fatal. Wet or sweaty hands make a dangerous connection when at the same time they are in contact with a good ground like a wet surface.

Actually, a lot of the strains on current-carrying parts of extension cords can be prevented by use of heavy-duty plugs, which are clamped to the cord. This is particularly helpful in cases where the cord is accidentally pulled or jerked. It is important to inspect extension cords often and, if they are damaged, tag them and do not use them.

References:

1926.403 General requirements

1926.404 Wiring design and protection

1926.405 Wiring methods, components, and equipment for general use

1926.406 Specific purpose equipment and installations

1926.407 Hazardous (classified) locations