Safety Sense

Do-It-Yourselfers Beware When Tackling Home Wiring Projects

 

While do-it-yourself (DIY) projects can be very satisfying to complete, they pose risks when it comes to electricity.

“Mistakes can be costly — or even deadly,” warns John Drengenberg, consumer affairs manager for Underwriters Laboratories, Inc. (UL), a Chicago, Ill.-based not-for-profit firm that tests and sets minimum standards for electric-consuming items. “The first and best safety tip is to call in an expert rather than be your own electrician.”

An ongoing study by the Quincy, Mass.-based Fire Protection Research Foundation has given UL engineers a better understanding of typical DIY wiring mistakes. The most common:

 1. Working with a live wire

 It may seem perfectly obvious, but thousands of DIYers receive electric shock injuries each year. To avoid becoming a statistic, always turn off the circuit breaker (or remove the fuse) before working on or replacing electrical equipment. If you have a pre-1940s home, be mindful that you probably have more than one breaker box, or panel board, as electricians call them. 

2. Using the wrong light bulb

Most lighting fixtures feature a sticker on the socket that tells you the proper type and maximum wattage of the light bulb to use. Installing a different type of bulb, or one with higher wattage, will not only make the room brighter, but could also damage the lights and cause a fire. Heat is usually the catalyst in this case: the higher the wattage, the hotter the bulb and the hotter the wire that goes to the lighting fixture.  

3. Not being grounded

For optimal safety, receptacles should be wired with the proper grounding and polarity. Generally, three-pronged outlets signify an effective ground path in the circuit. However, homes built before the mid-1960s probably don’t have a grounding path, and simply replacing the existing outlet with a three-pronged outlet won’t give you one.

“You see instances of this in homes with older wiring,” Drengenberg says. “It’s no worse than if you plug your two-pronged device into a two-pronged outlet. But it does give the homeowner a false sense of security.”

Wiring with a grounding path usually sports a copper grounding wire with the cable. If you are uncertain about whether your home’s wiring is grounded, inexpensive UL-listed outlet circuit testers are available to check for proper grounding and polarity. If your outlet is improperly grounded, call an electrician before moving forward in any project.  

4. Splicing, splicing, splicing

Always make sure your wiring size and type match. Splicing wires by simply twisting them together and covering them with electrical tape is rarely a good idea. Instead, use wiring suitable to your home’s wiring and place wiring connections in metal or plastic boxes to decrease fire risk.

Also keep in mind that circuits protected by 15-amp fuses or breakers should be wired with No. 14 AWG copper wire minimum. For 20 amps, use No. 12 AWG minimum-size copper wire. Other guidelines apply, so if you expect to do any splicing, seek professional help before you begin. 

5. Hooking new lights  to old wires

 Most light fixtures are marked with instructions for supply connections, such as “Use wire rated for at least 90C,” which refers to the maximum temperature — 90° Celsius or about 200° Fahrenheit — under which a wire’s insulation can safely be used. Again, if you have an older home (pre-1984, in this case), wiring may have a lower temperature rating than a new luminaire.

“This isn’t something most DIYers even think to consider,” Drengenberg cautions. “It probably won’t burst into flame immediately, but it does increase the risk of a fire.”

To avoid that risk, check your wire rating first, and either upgrade it or buy fixtures within the supply-connection range. 

For more electrical safety information, visit www.UL.com and explore the consumer perspective section.

 

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