What is aluminum wiring, how to identify, why is it risky and how to remediate

What is aluminum wiring, how to identify, why is it risky and how to remediate

Aluminum wiring is one of the types of electrical wiring which is done using conductors made up of Aluminum. Aluminum wiring was extensively used in the residential areas in the late 20th century, mostly from 1960s to 1970s. The use of Aluminum conductor was considered as an alternative to copper wires due to the increased prices of copper wires in late 20th century. Engineers and Electricians found the use of Aluminum conductors, instead of copper conductors, more reliable and more prevalent for the electrical installations in industrial buildings and homes at that time.

The provincial government of Ontario created a commission to investigate the use of aluminum wire in homes in 1977. The Commission recommended that aluminum wiring should continue to be approved for residential use after a thorough inquiry that lasted 18 months and included hearings and testimony.

In Ontario Canada, Aluminum was mostly used in 20th century and was considered reliable as per the Ontario Electric Safety Code. Ontario Electric Safety Code is a Canadian law that establishes safety requirements for electrical machinery setup and upkeep. Now due to potential hazards associated with Aluminum wiring, professionals have worked on the identification, risk analysis and remediation for safety. Let’s understand some facts related to Aluminum wiring.


Identification of Aluminum wiring

To resolve any issue, identification of problem is necessary. According to an estimation there are almost 450,000 houses in Canada that contain Aluminum wiring. Due to many safety concerns about Aluminum wiring, it became necessary to identify the type of wiring in houses and buildings. There are few tips to identify if your home contains Aluminum wiring.

  • Labeling: If wires were made before May 1977, then Aluminum wiring may contain the label such as “AL”, “Aluminum” or “ALUM” on the wire covering at a distance of every 12 inches as shown in the figure below. If wires were made after May 1977, then they may have labels such as Alum ACM, AL ACM or Aluminum ACM.

Figure: Labeling of Aluminum Wires


  • Coloring: To differentiate Aluminum wiring from copper wiring, Aluminum is usually made silver or gray in color.

Figure: Aluminum Wire

  • Construction Time Period: Homes or buildings built in 1960s to 1970s most probably have Aluminum wiring.
  • Special Service Connectors: Wall switches, special circuit breakers and connectors carrying the marking CU-AL are necessary for the Aluminum wiring. That can help to identify the wiring in buildings.

Figure: AL-CU Connector


Risks of Aluminum Wiring

Everything that has positive impacts also has negative impacts. Although the Aluminum wiring is cost effective, it has some risks associated with it that can cause safety concerns. Some of the risks are discussed below:

  • Thermal Expansion and Fire hazard: Aluminum expands due to thermal expansion and can cause loose connections and increase chances of sparkling.

Figure: Overheating due to thermal expansion of Aluminum wiring

  • Cold Creep: Cold creep is one of the most important issues associated with Aluminum wiring. Aluminum expands on heating and contracts when it cools down. Due to this property, it causes the connections to be lost.
  • Oxidation and Corrosion: Oxidation and corrosion are one of the major risks associated to Aluminum wiring. When Aluminum corrodes, it oxidizes more, and increases the electrical resistance and overheating.


Remediation for Aluminum Wiring

Following are the safety measures that can be taken if the buildings contain Aluminum Wiring:

  • Expert Opinion: Consult a professional for the assessment of the electrical system of your building and obtain recommendations on how to address risks.
  • Tightening of Connections: If there is no major problem, then application of antioxidants and tightening of connections can solve the problem.
  • Connectors: Electricians can use special connectors to apply a pigtail connection to avoid the aluminum wiring problem. Aluminum and copper wires can be safely connected with connectors in buildings in Ontario, reducing the risk of oxidation and thermal expansion.



To conclude, Aluminum wiring was a good solution in terms of cost in 1970s but due to the concerns related to safety, the use of Aluminum wiring has reduced a lot. The prevalence of Aluminum wire requires careful consideration of safety measures, which requires professionals’ assistance. Although by using special connectors, copper pig tailing and many other techniques, Aluminum wiring can be still used. But due to advancement of techniques it is not commonly in use after 1980s. even in Ontario Canada.

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