Most construction trades have an acceptable fudge factor. A few trim joints could be tighter, some of the painting neater, a stair tread less squeaky.
Even new houses come with parts that are not quite right but considered close enough — except for the wiring.
There's no acceptable allowance for a switch or an outlet that almost always works. Because of the dangers from electrical shock and fire, wiring is the most closely controlled construction trade. It's zero tolerance, and why we expect the systems to work correctly all the time.
But some components deteriorate with age. Others become outdated compared with safer products that meet current codes. The electrical system does have some weak links long term. But before you check into those problems, the first step in many homes is to sort out the circuits so you know where to look.
Breakers in the main panel should line up logically, room by room, and be neatly labeled. More often, and particularly in renovated homes, circuits are a confusing maze. Half the kitchen is on the No. 1 breaker and the other half is on No. 12. Improvements and additions over the years can create a jumble.
To sort it out, you could work with a partner: Try a lamp or radio in outlet after outlet, flip different breakers and shout back and forth about what's on and what's off. That trial-and-error approach takes a long time, may produce some errors and you'll have to reset the cable box, clocks and maybe reprogram the thermostat when you're done.
Or you could use a tracer tool like the Sperry Instruments Breaker Finder (model CS61200, about $40). The battery-powered tool has two parts that snap together for storage. The base is a transmitter that plugs into an outlet and sends a signal through the wires. The receiver has a wand to move over different circuit breakers in the main panel until it picks up the signal. You have a match when an LED indicator on the receiver lights up and the unit starts beeping.
Once you have the layout pinned down, check these signs to see if your wiring system is overloaded, deteriorating or too old to be as safe as it should be. There are three giveaways:
Several duplex outlets (space for two plugs) have adapters connected to more than two plugs.
The system has permanent extension cords.
To keep the circuit breaker from tripping, you have to unplug something to run something else.
These conditions indicate that you need more outlets, maybe a new circuit and possibly a larger service, which is a major project that brings more power from the street to the main breaker panel.
Age and condition
The safety threshold for typical household wiring is about 40 years. Some wiring lasts longer, but with increased risks.
Warning signs include any damage to the wire insulation, most often cracking caused by brittleness. That problem usually surfaces first in an unconditioned area of the house like a cold crawl space or an attic where temperatures soar in the summer. Wire leads are stripped of insulation where they attach to outlets and switches. But those locations are shielded by boxes mounted inside the wall. Exposed metal wiring anywhere else is dangerous.
Older systems, even in good condition, may also lack modern components that increase safety. For example, ground fault circuit interrupters are quick-tripping breakers now installed near any wet locations. They cut the power faster than a circuit breaker in the main panel and greatly decrease the risks from electrical shock. If your house doesn't have them but does have signs of deterioration or overloading, it's time to call an electrician.
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