Your home’s electrical wiring can be damaged by many different elements, including rodents, age, and corrosion. Because an older home’s electrical system is grandfathered in every time the electrical code is revised, your home’s electrical wiring may violate safety codes without your knowledge. Here are some dangers for home electrical wiring, as well as ways to prevent and treat any damages that may happen. Please note: if you’re going to work with your home’s electrical wiring, always turn off the circuits at the main breaker panel for safety before you begin work.
Knob and Tube Wiring
Knob and tube was one of the earliest types of residential wiring systems. It featured a cloth-covered hot wire and a neutral wire that were run parallel to each other. These wires were anchored to the house using ceramic knobs and tubes. This older wiring can’t be grounded or spliced into a grounded circuit, and the soldered connections can melt if they encounter too much current. Any circuits that are covered with building insulation need to be rewired or disconnected because they can easily overheat or catch fire.
Armored Cable Wiring
Armored cable was the next advancement in wiring after knob and tube. In this type of wiring, hot and neutral wires are covered with a flexible steel sheath, which is then insulated using cloth-covered rubber. The sheath is grounded, so it’s easy to retrofit grounded receptacles with this type of wiring. The sheath absolutely must be anchored to a metal outlet box for safety. The insulation can degrade over time or if it’s exposed to too much current in the circuit, so check the insulation’s condition every few years to make sure it’s still safe.
In the 1960s and 1970s, aluminum wire was an inexpensive substitute for copper, but it’s no longer considered safe for homeowners. Aluminum corrodes when it comes into contact with copper. This leads to loose connections, which can cause arcing and fires. You can retrofit a dielectric wire nut on the copper and aluminum connection in light fixtures, which stops the corrosion while maintaining the conductivity. If you install any replacement switches or receptacles, make sure they’re AL-compatible.
The wires located in the back of switches and receptacles are more likely to come loose than the wires that are nearer to the screw terminals. These loose wires in the back can make the receptacle or switch stop working, and they can also start fires. To look for backstabbed connections, remove the switch or receptacle from the outlet box. One backstabbed connection means that there are probably more in the house. Release any backstabbed wires, attaching them to the proper screw terminals on the switch or receptacle.
Many of “unknown origin” house fires are likely caused by rodents chewing on electrical wires. Rodents chew on anything that’s available because their teeth are constantly growing and they need to keep them filed down. When rodents chew on electrical wires, they strip away the plastic insulation, revealing the hot metal wiring underneath. The exposed metal can short-circuit or spark and ignite its flammable surroundings. Since mice can squeeze through openings smaller than a quarter of an inch, you’re going to need a professional exterminator to seal up any entrances that a rodent could possibly use. If an exterminator sees any evidence of rodent damage or gnawed wires, call an electrician immediately.
As with any electrical work, make sure you call a professional if you need to, and take all the necessary safety precautions whenever working with electrical systems.