Know Your Home’s Wiring

Help prevent wiring from sparking an electrical fire.

Your home’s wiring is hidden, so it can be difficult to spot problems before it’s too late. However, familiarizing yourself with how wiring works and learning warning signs can help you detect issues early and avoid costly damage caused by electrical fires.

How Wiring Works

Your home’s wiring starts at the service panel, which delivers electricity to different areas of the house. The service panel also helps prevent wires from overheating and causing an electrical fire. When a surge occurs, a circuit breaker within the panel trips or a fuse blows to shut down power.

How electricity travels from the service panel throughout the house depends on the type of wiring system in place. There are three types:

  • Knob-and-tube: This system uses porcelain tubes to protect insulated copper wire conductors and is supported by porcelain knobs nailed to the lumber. This type of wiring was installed in homes through the 1940’s. Due to its age and lack of grounding, knob-and-tube wiring is considered a fire hazard.
  • Aluminum: This was used as an inexpensive replacement for copper in the 1960’s and 1970’s. Though cheaper, aluminum wiring can be a fire risk because overheating can occur where the wire attaches to outlets and other fixtures.
  • Grounded: This system was first installed in homes in the 1940’s, and it’s still used today. It’s considered the safest wiring system because it safeguards against electric shock.

How to Identify Wiring Hazards

Have a qualified electrician periodically inspect the wiring in your home—especially if it is more than 40 years old. If you’re not sure when the wiring was last inspected, look for a date and electrician’s signature on the service panel door.

You also can regularly review your home’s electrical system for signs that wiring is failing or no longer meets your needs. Contact a professional if you notice any of the following warnings:

  • Signs of outdated wiring (noted above)
  • Lack of grounded, three-prong outlets; tamper-resistant outlets; and ground-fault circuit interrupters, which should be located in garages, outdoor spaces and damp areas of the house
  • Lights that flicker or dim
  • Circuits that trip or fuses that blow repeatedly
  • Crackling, sizzling or buzzing sounds coming from the electrical system
  • Warm or discolored outlets
  • Cords that feel hot to the touch
  • A burning smell
  • Arcing or sparking when plugging cords into outlets
  • Getting shocked when you touch switches, outlets or appliances
  • Cracked or frayed wires, or signs that rodents have chewed on wires
  • Smoking outlets or appliances