Everyone has been through a blackout when clocks stop, televisions go dark and the array of machines that cool, heat, clean, wash and dry won't run.
It's always a little surprising because people expect electricity and wiring to work properly and indefinitely.
When power lines topple, conditions are beyond your control. But problems also arise inside, usually due to one of the top-ten electrical hazards identified by the Copper Development Association (CDA), a trade group that deals with residential electrical systems.
This week we'll look into some of the problems, including signs of trouble and solutions. Next week we'll cover the rest, plus new equipment, missing from most homes, that is or soon will be required by code.
• Old wiring. Dated systems typically show their age with frayed wires, brittle and crumbling wire insulation, and faulty switches -- one part of the system that can suffer mechanical breakdowns from years of being turned on and off.
Overall, the safety threshold for household wiring is about 40 years, according to the CDA. Properly installed wiring may serve trouble-free longer than that but won't provide the safety or capacity specified in modern codes. If you haven't upgraded the system in an older house (probably 100 amps or less), 40 years is certainly time for a checkup.
Most hazards are due to poor workmanship in the original installation, but even more so to updating by homeowners and incompetent professionals, says the CDA. There is no periodic re-inspection procedure, and unsafe changes may not be discovered until a house is sold or improved in a way that requires a building permit.
When should you have wiring checked by a licensed electrician, even if the system is working properly? If your home is over the 40-year line, or if you're not the original owner of a home with nonstandard (probably added) outlets, switches, or circuit wiring in the main panel.
If you find unexploded bombs such as zip cord (small-gauge extension cord wire) buried in the wall, you need the electrician yesterday.
• Dated wire size. Decades ago, houses didn't use as much electricity as they do today. (The Department of Energy says energy use in homes has increased fourfold from the '50s to the '90s.) Central air conditioning built into most new houses consumes a lot. The ever-increasing number of appliances does, too.
The upshot is that many older homes have wiring designed to carry smaller electrical loads, typically 14 AWG (American Wire Gauge), suited to handle 15 amps, the limit of then-typical household circuits.
If the sizes and numbers are puzzling, think of the garden-hose analogy: A large-diameter hose carries more water than a small one, just as a thick wire carries more power than a thin one.
Unfortunately, the AWG system only adds to the confusion because of its inverse ratings: the larger the wire, the smaller the number. That means modern 10- or 12-gauge wiring is thicker, not thinner, than 14- or 16-gauge.
Size isn't significant with a garden hose -- if you try to pour more water through a smaller diameter, it just won't go. But the difference is crucial with wiring. If you try to carry more power through a smaller wire, the wire heats up and that causes all kinds of trouble, including house fires.
Complete rewiring is a daunting project. It also requires a skilled electrician who can pull new lines through existing pathways instead of chopping up your house for access. But consider upgrading to 10- or 12-gauge in high-use areas such as kitchens and utility rooms. If you routinely pop circuit breakers, upgrading is essential.
• Inadequate circuits and outlets. Homes only 20 years old may be under-wired in another way -- with minimal circuits and outlets that can't handle all the appliances, not to mention extras such as home-office equipment. When the system falls short, temporary extension cords can become permanent fixtures.
With breakers protecting branch circuits and outlets, even a limited layout generally proves more inconvenient than unsafe. Hazards are more likely to stem from the extension cords.
The best fix is a new circuit to power new outlets in heavy-demand areas. Sometimes an existing line can be split, creating two circuits, each with its own breaker.
• Too many extension cords. Many houses have tangles of extension cords ingeniously rigged from one outlet to a stunning amount of equipment. If only one or two appliances run at the same time, there's no problem -- and a breaker should trip if the load is excessive.
But as the CDA puts it, extension cords should seldom be needed in an adequately wired house. Tucked under carpeting, they become a common cause of house fires. And to power appliances through extension cords, people often clip polarized plugs and grounding prongs, defeating basic safety features.
Aside from frays and cracks (those cords should be replaced immediately) the main telltale is heat, a sure sign of overloading. Using a thicker cord will help -- 16 gauge or lower, instead of 18 gauge. But upgrading with additional power, circuits and outlets is a more convenient and much safer solution.
