The Story Behind Aluminum Wiring
Aluminum wiring in homes was common from the mid 1960’s to mid 1970’s, and was used as a cost effective alternative to copper wiring when the price of copper was very high.
Clients and realtors will often have concerns that this type of wiring is unsafe and that if aluminum wiring is found during a home inspection, it needs to be replaced. The short answer is that aluminum wiring is safe and still approved for use in residential applications, however there are some special considerations a homeowner should be aware of.
Shortly after aluminum wiring became popular, several common problems began to emerge, including flickering lights, warm cover plates at switches on outlets, and burned wiring. These warning signs are caused by some inherent problems with early aluminum wiring.
- Softness – Aluminum is much softer than copper, and electricians that were used to working with cover found that aluminum was very easy to nick, stretch, cut or crush. Damaged wire can reduce the diameter of the wire, creating the potential for hot spots, leading to overheating.
- Creeping – Aluminum wiring is susceptible to changes in temperature. As the wire heats up under load, it expands, and contracts when it cools down. Repeated expansion and contraction can cause the connection to loosen at a junction, outlet, switch, or in the panel. Loose connections lead to overheating.
- Oxidization (Rust) – Metals can rust or oxidize when they come into contact with moisture or air. Aluminum is more prone to rusting than copper, and problems arise because the rust that forms on aluminum is a poor electrical conductor that leads to overheating.
Beginning in 1972, the alloy used in aluminum wiring was improved to better suit the conductor for electrical work. Special outlets, switches, and crimping connection techniques have also been introduced, designed to maintain proper conductivity at connections.
What to do if aluminum wiring is found by your home inspector.
Aluminum wiring, when it has been properly installed, inspected and maintained, is safe for use in your home. If an aluminum system has been in the home for 50+ years with no modifications and no issues have arisen, there is very little danger. Problems arise now when homeowners or unqualified contractors make changes to the aluminum electrical system, and connections or devices are installed that are not compatible with aluminum. For example, the modern “decora” type receptacles, often replaced by homeowners, are typically not compatible with direct connections to aluminum. Improper installation techniques will create the potential for the problems with aluminum to manifest, leading to fire hazards. When aluminum wiring is found by your inspector, they may inspect a small number of connections looking for safety concerns, but it is recommended that a qualified electrician do a full audit of all aluminum circuits to ensure that any modifications have been performed correctly.
Other implications – your insurance company may be hesitant to insure homes with aluminum wiring, or charge a higher premium for coverage, unless the electrical system has been fully inspected and any required repairs conducted.