Dealing with the aluminum wiring issue is like walking on a bed of hot coals. On one side are some independent home inspectors, electricians, and others telling you it’s bad stuff, have it replaced with copper. On the other side is a code enforcement inspector stating that he has seen very few problems and the electrical codes and that aluminum wiring is OK. Where is the truth and why is there such confusion?
Potential problems with aluminum wiring
On April 28, 1974, two people died in a home fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet. Since that tragic accident, the U.S. Consumer Products Safety Commission and other government agencies have investigated numerous complaints throughout the nation relating to trouble with small gauge aluminum branch circuit wiring. The Commission has also had research conducted that shows that homes wired with aluminum wire manufactured before 1972 (“old technology” aluminum wire) are 55 times more likely to have one or more connections reach “Fire Hazard Conditions” than is a home wired with copper.
It’s OK and it’s not OK. Is that clear?
Plainly stated, aluminum “wire” is fine. Small gauge aluminum branch circuit wiring installed prior to 1972 and improper installations after 1972 may not be. The issue is not the wire but is the wiring connections on small gauge circuits. Aluminum wiring, properly installed and meeting current industry standards and code requirements, should be perfectly safe.
Aluminum wire does not behave the same way as copper wire. The installation procedures are different. Prior to 1972 aluminum wiring was installed the same as copper wire. Some electricians today and most amateurs have failed to observe the different requirements. Aluminum wire has approximately a 30 percent higher expansion/contraction rate than copper (it moves more). When aluminum wire is exposed to the atmosphere, a film of aluminum oxide (like rust, only white) forms on the metal surface. The oxide is an insulator, not a conductor of electricity. These two properties, working together, cause the problems. As the oxidation continues to build up on the wire, it builds resistance.
Heat comes with the resistance melting the insulation. The expansion/contraction rate of aluminum wire loosens the connection points causing arcing and short circuits. These two factors are what can cause fires.
Simply stated, white rust forms on the bare wire at the connections causing the wire to overheat melting the insulation of the covered wire. The rust lubricates the connection and as the wire moves with changes in temperature the connection works loose causing sparks. One of the two starts a fire.
This oxidation and movement are not as much of a problem in stranded wire (multiple wires stranded together) where high voltages are involved. However, oxidation is a problem with residential wiring because the current is supplied at a much lower voltage in a solid conductor (non-stranded) wire.
Can It Be Fixed?
Yes it can. In fact, there are several solutions:
The most expensive repair is to rewire with copper wire leaving the old aluminum wire in place or removing it. This is not only the most expensive, but also the most difficult. It is difficult to rewire most homes without removing wall finishes in many locations. Many people pay to have this done. They are convinced the wire is the problem which, as stated above, is not the case. Many repair companies prefer this method for one reason. They make more profit.
Homes built before 1965 are unlikely to have aluminum branch circuit wiring. Homes built, rooms added, and circuits rewired or added between 1965 and 1973 are more likely to contain aluminum wiring installed using the old technology. The issues found in wiring installed after 1972 are failure to use devices rated “CO/ALR” and failure to use or properly use an antioxidant compound to protect the wire. Servicing and repair of connection points along with removal and replacement of devices is often a much more cost effective option for the home owner.
Aluminum wire is still in the National Electric Code. Some cities have passed an ordinance restricting aluminum wire use, but the ordinance affects only construction from the date the ordinance went into effect. All homes built before those dates are grandfathered in. If Affordable Inspections observes a problem, we will report it but we do not have the authority to determine the type of repair. The problem should be investigated and if necessary repaired by a licensed electrical contractor.