Aluminum wire is a type of wiring used in houses and by service men in their power grids for electrical transmission since the early 1900s and was preferred over copper wires since they had cost and weight advantages. They are still the preferred material today for transmission and distribution applications. However, there are a number of danger hazards to having aluminum wiring in your home that could result in damage, injury or even death.
In branched circuit wiring, the typical connections from electrical wire to devices (terminals) are made by wrapping the wire around screw terminals and tightening the screw. The terminals to aluminum wires began to fail over time due to improper connection techniques and dissimilar metals having different resistances and different coefficients of thermal expansion. Because of these failures, heat is generated under electrical load and causes overheated connections which resulted in many house fires.
Because of the fact that aluminum and copper are dissimilar metals, this presents a danger when joining aluminum wire and copper wire since it causes galvanic corrosion in the presence of an electrolyte and these connections become unstable over time
When exposed to air most metals would oxidize freely. Aluminum oxide is an electrical insulator and not an electrical conductor. Thus, the electron flow through the oxide layer can be severely obstructed. Under most conditions the added resistance is not noticeable.
The aluminum wires used before the mid – 1970s had a coefficient of expansion that varies significantly from the metals commonly found in devices, outlets etc. Aluminum wires installed in the 1960s and 1970s continue to operate without any problems. However, issues tend to arise in the future and some connections were not properly made when installed, this would cause a huge influx in the dire need of tenant improvement specialists. There are also problems with connections made by applying too much torque since this causes damage to the wire
Connections between aluminum and steel tend to loosen and get worst over time due to the different expansion and contraction rates of aluminum and steel under thermal load. This loosening cycle results in overheating and allowing intermetallic steel/aluminum alloying to occur between the conductor and the screw terminal which causes a high resistance junction leading to additional overheating. The end result of which is a fire. The problems associated with aluminum wires are typically with the pre – 1970s solid wire smaller than No. 8 AWG since the properties of that wire result in significantly more expansion and contraction than a modern day aluminum wire. The older aluminum wire have a problem with a property called creep. This property made the wire permanently deform or relax over time under load
Home hazard insurance do not cover homes with any aluminum wiring in some states of the US and other insurance companies that claim to cover it charge a higher premium than for homes with copper wiring.
Aluminum wiring can be replaced or repaired to effectively and permanently reduce the possibility of fire and injury due to failing (overheating) wire connections and splices. It is highly recommended that you hire a qualified electrician who is experienced and well informed about aluminum wiring hazards and only uses approved aluminum wiring repair connectors.