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  • Home wiring health check

    How to tell if your home’s wiring is over the hill

    This improperly wired overhead lamp switch reveals a potential home danger. Electrical code requires wire nuts for connections, but these ­connections have been taped. The wires could become exposed and touch the lamp’s metal base, resulting in electrical shock.  Source: Underwriters Laboratories

    This improperly wired overhead lamp switch reveals a potential home danger. Electrical code requires wire nuts for connections, but these ­connections have been taped. The wires could become exposed and touch the lamp’s metal base, resulting in electrical shock.
    Source: Underwriters Laboratories

    Electric capacity is a major concern with older wiring systems. Homeowners in the 1930s didn’t use a lot of elec­trical appliances, except for a refrigerator, a few lights, and a radio. An explosion of appliance purchases followed in the late 1940s and early ’50s. But the arrival of air ­conditioning during the 1960s soon rendered many mid-century home elec­trical systems obsolete. More recently, residences built as little as 20 years ago might be insufficient for handling entertainment systems, personal computers and everything we plug in to recharge.

    John Drengenberg, Consumer Affairs Manager for Underwriters Laboratories, Inc., (UL), an indepen­dent ­product safety testing and cer­tification ­organization based in Chicago, Ill., says, “Homeowners should not assume all is well simply because fuses aren’t ­blowing, circuit breakers aren’t ­tripping, or they’re not receiving shocks or smelling burnt plastic. Inside the walls, wire ­insulation could be cracking and crumbling, especially if wires are drawing more current than they were designed to handle.”

    To avoid such hazards, consumers should understand the limits of home wiring systems. Often, this depends on when a home was built, or if the electrical system was upgraded. In other cases, though, telltale signs may ­indicate a problem.

    “Anytime you receive a shock from an electrical appliance, outlet or wall switch in your home, it’s a warning that you should talk with a qualified electrician,” Drengenberg cautions. “If a fuse blows or a circuit breaker trips right after you replace or reset it, you have trouble somewhere. Flickering or dimming lights could mean loose ­connections, overloaded circuits, improper wiring, or arcing and ­sparking inside walls.”

    In older homes, heat means too much electrical current’s being drawn through outlets. “If your receptacles or plugs are hot to the touch — you can’t keep your hand on them for more than five seconds — you may have an ­overload,” Drengenberg advises.

    When too much current gets drawn, wires heat up, baking and eventually weakening the insulation. Wires with damaged, decayed or brittle insulation can lead to shocks and fires.

    Another issue associated with older home wiring systems is the number of receptacles in each room. Today’s electrical code requires outlets be placed every 12 feet of running wall space, about one per wall in the ­average 10-by-12-foot room. “Relying on extension cords is not the answer,” says Drengenberg. “Extension cords are meant for tem­porary use only and should not be a substitute for per­manent wiring.”

    Every home electrical ­system should have some type of ­grounding. Newer homes are wired with cables that include a ground wire, and proper grounding ­prevents deadly electrical shocks. Having a properly bonded grounding system is also key to surge protection for your com­puters and all appliances. The ground wire allows for use of three-pronged receptacles needed to safely power certain ­appliances, par­ticularly ones with metal shells, such as ­refrigerators and washing machines.

    Many wiring systems installed in the 1950s, and earlier, lacked a ground wire. Homes from this era have only two-pronged outlets, unsuitable for many modern conveniences. Simply replacing two-pronged receptacles with three-pronged receptacles violates the National Electrical Safety Code if no ground path exists.

    In some cases, older homes may ­feature newer wiring systems. But the era when the wiring was upgraded impacts electrical limitations. Before buying a home have someone certified in electrical work inspect the system to be safe. Visit www.inspectorseek.com for referrals. 

    Source: Underwriters Laboratories, Inc.

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