Staying Current

When you plug in a new appliance, dial up the air, or switch on a reading lamp, you likely don’t give much thought to the wires carrying the electricity.

Few people do — and that can be at your own risk. It’s important to pay attention to your home’s wiring, whenever it was built, but particularly if it’s an older house. In the United States each year, an estimated 39,000 house fires and 350 deaths are caused by faulty home wiring and other electrical equipment malfunctions, such as extension cords, lighting, and plugs, the National Fire Protection Association reports.

The nation’s housing supply is aging. A third of all homes are 50-plus years old; half have been standing for at least 30 years. Those statistics are important, given that older homes often fall short of today’s electrical-safety standards and were not designed to handle the rising electrical demand.

Problems with existing electrical systems — worn-out equipment and “fixes” by previous owners — may never be discovered. Furthermore, most communities don’t require an electrical inspection when a property changes hands.

How do you take stock of your home? What hazards should you look for?

In the oldest homes — those built a century or more ago — electricity was a retrofit, installed mainly for lighting, sometimes with wiring running through former gas-lighting pipes or porcelain tubes. Typically, such houses were wired at just 30 amps, enough to power basic lighting and some kitchen appliances, but little else.

By the late 1940s, 60-amp service was common — better, but still short of the 150- to 200-amp service typical of today’s construction. (In the largest new homes, 800-amp service and up isn’t uncommon.)

Old wiring by itself doesn’t necessarily spell trouble. But homeowners should be mindful that the insulation protecting the wiring is in good shape.

Another problem with older homes is that often they’re not grounded. (A wire leading from the electrical service panel to the ground outside minimizes the risk of shocks.) Older homes also often have too few outlets for today’s demands. Some homes have as few as one outlet per room, which can lead to a risky reliance on extension cords.

Beginning in the 1950s, wires were insulated with tougher thermal plastic instead of fabric or rubber; three-prong grounded outlets replaced two-prong types; and circuit-breaker panels replaced fuse boxes.

Both circuit breakers and fuses are designed to shut off power to their circuits if more current flows through circuits than they should carry. Experts consider circuit breakers more convenient and safer because they’re more tamper-resistant.

When fuses blow, circuit breakers repeatedly trip, or lights will dim, signaling a problem with the wiring or indicating an over-stressed circuit.

Electrical fires can occur from a phenomenon called “arcing,” in which current “jumps” through a tiny gap of air, such as between two ends of a broken wire or at a loose connection to a receptacle. Arcs are extremely hot and can  heat nearby material, such as wood or some types of insulation, which can smolder for hours before bursting into flames.

Another potential problem affects some homes built between the mid-1960s and mid-’70s, when builders substituted less expensive aluminum wiring for standard copper wiring in the branch circuits. It was later found to oxidize and loosen at connections, causing arcs and overheating at switches, outlets, and the breaker panel.

If you’re experiencing flickering lights, hot outlets, or other warning signs, disconnect appliances on overworked circuits. Then hire a qualified, licensed electrician to inspect your home and make repairs. To find a reputable electrician or seek recommendations from satisfied neighbors, visit b