Single-strand aluminum wiring

Single-strand aluminum wiring was sometimes used in place of copper for electrical branch circuit wiring in residential construction between the mid-1960’s and mid-1970’s. Since about 1973, use of single-strand aluminum wiring has largely ceased due to problems with the material.
 
Problems with single-strand aluminum wiring
According to the Consumer Product Safety Commission (CPSC), homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach "fire hazard conditions" than a home wired with copper.
 
Some of the common problems with single-strand aluminum wiring are: (1) Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper and over time can cause connections to loosen. (2) Aluminum wire is more susceptible to oxidation than copper wire. The aluminum oxide formed by the oxidation process can deteriorate connections and present a fire hazard. (3) Aluminum is more susceptible to fatigue and failure from bending and other forms of abuse than copper. Metal fatigue causes the aluminum wire to break down internally and increases the wire’s resistance to electrical current, leading to a buildup of excessive heat. (4) Contact with moisture or dissimilar metals can cause the aluminum to corrode. (5) Single-strand aluminum wiring can be damaged by over-tightening screws that connect the wiring to breakers or other electrical components. The wire will continue to deform even after the tightening has ceased and this creates a loose connection and increases electrical resistance in that location.
 
Identifying Aluminum Wiring
Standards of Practice for the Commonwealth of Virginia and the International Association of Certified Home Inspectors (InterNACHI) require the home inspector to report on single-strand, solid conductor aluminum branch-circuit wiring, if observed by the home inspector.
 
One clue for the inspector will be the age of the house. Homes built or expanded between 1965 and 1973 are more likely to have aluminum wiring than houses built before or after those years. On visible sections of wiring, the plastic wire jacket may be marked with the word “aluminum," the initials "AL," or a specific brand name, such as "Kaiser Aluminum." 
 
Evaluation and corrective action
Aluminum wiring should be evaluated by a qualified licensed electrician who is experienced in evaluating and correcting aluminum wiring problems. Not all licensed electricians are properly trained to deal with defective aluminum wiring.
 
Conclusion
Aluminum wiring can be a fire hazard due to inherent qualities of the metal. Inspectors may suggest that their clients talk with their insurance agents about whether the presence of aluminum wiring in the client's home is an issue that would require changes to their policy language.
 
Call us – we’ve got experience in locating and identifying single-strand aluminum wiring.