Introduction and Overview of Aluminum Building Wiring
– Aluminum wire has been used for electrical conductors in power transmission lines since the late 1880s.
– Aluminum wire requires a larger gauge than copper wire to carry the same current.
– Aluminum alloys used for electrical conductors are approximately 61% as conductive as copper.
– Aluminum wires are one-sixth the cost of copper wire of the same conductivity.
– The lower weight of aluminum wires makes them well-suited for use in power distribution systems.
– Aluminum building wiring for modern construction is manufactured with AA-8000 series aluminum alloy.
– Larger gauge stranded aluminum wire is commonly used in residential construction.
– Aluminum wire is used for service feeders and larger branch circuits.
– Terminations for aluminum wire can be problematic, especially with twist-on connectors.
– Solid aluminum wires made with AA-8000 series alloy are allowed for 15-A or 20-A branch circuit wiring.
– Older homes may have solid aluminum branch circuit wiring.
– Utility grade AA-1350 alloy aluminum wire was used in branch circuits.
– Older aluminum wiring installations may present a potential fire hazard.
– Revised manufacturing standards were developed to reduce issues with aluminum wiring.
– Aluminum wiring made with newer alloys performs mechanically like copper.
– Aluminum wire is used in power grids for overhead power transmission lines and local power distribution lines.
– Aluminum provides a better conductivity-to-weight ratio than copper.
– Aluminum has been used by utility companies for electrical transmission since the late 1800s.
– Aluminum wires have cost and weight advantages over copper wires.
– Aluminum is still the preferred wire material for power transmission and distribution applications.
– Aluminum or Copper-clad aluminium wire was used for wiring in communist East Germany due to the high cost of copper.
– Aluminum building wire was used in North American residential construction during a period of high copper prices.
– Electrical devices at the time were not designed for aluminum wire, leading to issues.
– The use of older AA-1350 alloy aluminum wire in branch circuits had mechanical properties that made it more susceptible to failures.
– The 1977 Beverly Hills Supper Club fire was triggered by poorly-installed aluminum wiring.
Problems with Solid Aluminum Wiring
– Solid aluminum wiring in residential construction has resulted in failures of connections at electrical devices.
– It has been implicated in house fires, according to the U.S. Consumer Product Safety Commission (CPSC).
– Obtaining homeowners insurance for a house with older aluminum wiring may be difficult in some areas.
– Improper installations and the differences in coefficient of expansion between aluminum wire and terminations are the main reasons for connection failures.
– The reported hazards are associated with older solid aluminum branch circuit wiring.
– Improper installation includes not abrading the wires, not applying a corrosion inhibitor, and not wrapping wires around terminal screws correctly.
– Inadequate torque on connection screws can cause damage to the wire.
– Poor workmanship can lead to problems in the future, even if the initial installation was properly done.
– Connections made with too much torque on the connection screw can also damage the wire.
– Soft aluminum wire is particularly susceptible to damage from excessive torque.
– Older solid aluminum wire has a higher coefficient of expansion compared to copper wire or modern aluminum wire.
– Creep, the permanent deformation or relaxation of the wire over time under load, is a significant issue with older aluminum wire.
– Aluminum wire and steel screws used for terminations expand and contract at significantly different rates under thermal load.
– Loose connections can occur due to inadequate torque and creep of the aluminum wire.
– Formation of intermetallic steel/aluminum compounds between the conductor and the terminal screw leads to higher resistance junctions and overheating.
– Many electrical devices used in the 1960s had smaller plain steel terminal screws, making them vulnerable to problems with aluminum wire.
– The CU/AL specification was created to address the use of aluminum wire, but it was not effective.
– The CO/ALR specification was introduced with brass screw terminals designed to act as a similar metal to aluminum.
– CO/ALR-rated devices have deeper undercuts in the screws to securely hold the wire.
– CU/AL is the standard connection marking for circuit breakers and larger equipment.
– Aluminum oxide is an electrical insulator, impeding the flow of electrons through the oxide layer.
– Proper termination of aluminum wire breaks the oxide layer to form an excellent electrical connection.
– Inadequate torque or use of non-rated devices can result in inadequate connections and additional oxide formation.
– Joining aluminum and copper wires can lead to galvanic corrosion over time.
– Oxidation was found not to be a substantial factor in failures of aluminum wire terminations.
Repair Methods for Aluminum Wiring
– Pig-tailing involves attaching a copper wire to the existing aluminum wire.
– Special crimp connectors, miniature lug-type connectors, or twist-on connectors can be used for the splice.
– Pig-tailing saves time and money.
– The U.S. Consumer Product Safety Commission (CPSC) recommends COPALUM connectors or AlumiConn connectors for permanent repairs.
– Twist-on connectors with antioxidant compound can be used as a temporary repair.
– COPALUM connectors create a cold weld between copper and aluminum wire.
– Considered a permanent, maintenance-free repair.
– Limited space in enclosures may require additional measures.
– Costly to install and require certified electricians.
– Difficult to find local electricians certified to install these connectors.
– AlumiConn connectors are miniature lug connectors used for permanent repair.
– Special torque screwdriver is the only required tool for installation.
– Proper torque on set screws is critical for an acceptable repair.
– Limited enclosure space can be a challenge.
– Relatively newer repair option compared to other methods.
– Twist-on connectors pre-filled with antioxidant compound for joining aluminum to copper wire.
– Ideal no. 65 Twister Al/Cu wire connector is the only UL Listed connector in the U.S.
– Distinctive purple color for easy identification.
– Considered a temporary repair by the CPSC.
– Manufacturer’s instructions may differ from CPSC recommendations.
– CO/ALR Source: https://en.wikipedia.org/wiki/Aluminum_building_wiring
The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (March 2022) |
Aluminum building wiring is a type of electrical wiring for residential construction or houses that uses aluminum electrical conductors. Aluminum provides a better conductivity-to-weight ratio than copper, and therefore is also used for wiring power grids, including overhead power transmission lines and local power distribution lines, as well as for power wiring of some airplanes. Utility companies have used aluminum wire for electrical transmission in power grids since around the late 1800s to the early 1900s. It has cost and weight advantages over copper wires. Aluminum in power transmission and distribution applications is still the preferred wire material today.
In North American residential construction, aluminum wire was used for wiring entire houses for a short time from the 1960s to the mid-1970s during a period of high copper prices. Electrical devices (outlets, switches, lighting, fans, etc.) at the time were not designed with the particular properties of the aluminum wire being used in mind, and there were some issues related to the properties of the wire itself, making the installations with aluminum wire much more susceptible to problems. Revised manufacturing standards for both the wire and the devices were developed to reduce the problems. Existing homes with this older aluminum wiring used in branch circuits present a potential fire hazard.
In communist former East Germany (GDR, 1945-1990), aluminum or Copper-clad aluminium wire (″AlCu-Kabel″) had to be used for wiring as copper was expensive to import. While all devices were designed for aluminum during that era, this ended with unification in 1990 when standard Western European equipment became available and the national public owned enterprises (Volkseigener Betrieb) went out of business.
