Aluminium Wiring in 1960s and 1970s London Properties: Risks and Remediation
A significant number of London properties built or rewired during the 1960s and 1970s contain aluminium wiring rather than the copper wiring used in most modern installations. Aluminium wiring carries specific risks that homeowners need to understand, and specific remediation options that should be considered as part of any electrical safety review.
Why Aluminium Wiring Was Used in London Properties
During the 1960s and into the early 1970s, there was a period in which the price of copper, the standard conductor material for electrical wiring, rose substantially relative to the price of aluminium. Electrical installation contractors and housing developers in the United Kingdom, including London, switched to aluminium wiring for some residential and commercial projects during this period as a cost-saving measure. The switch was not accompanied by changes to fittings, terminals, or installation practices designed to accommodate the different physical properties of aluminium, which led over time to the development of safety problems that are now well understood but that require specific attention in properties where the aluminium wiring remains in place.
The period of aluminium wiring use in UK domestic installations was relatively brief, predominantly from the mid-1960s to the mid-1970s, and was followed by a return to copper as the standard when copper prices fell. As a result, not all London properties of this era contain aluminium wiring, and the presence of aluminium wiring in a specific property depends on which contractor installed it and the procurement decisions made at the time. Homeowners of properties built or substantially rewired between approximately 1965 and 1975 should have the installation inspected to establish whether aluminium conductors are present. An EICR carried out by a competent electrician will identify aluminium wiring in the course of the inspection.
The Specific Risks Associated with Aluminium Wiring
Aluminium as a conductor has properties that differ from copper in ways that create installation risks if not properly managed. Aluminium expands and contracts more than copper with temperature changes during load cycling, which causes connections that were tight at installation to loosen over time, creating high-resistance connections that generate heat locally. Aluminium also oxidises readily when exposed to air at connection points, forming aluminium oxide, which is a poor electrical conductor and further increases connection resistance. The combination of loosening connections and oxidation at connection points means that aluminium wiring installations that have not been maintained or upgraded develop hot spots at terminals, switches, and socket outlets over time.
The risk from aluminium wiring is not inherent to aluminium as a conductor material, which is used safely in high-voltage overhead transmission lines and in large-section building wiring where it is properly specified and terminated. The risk in domestic London properties arises specifically from the use of aluminium conductors in small-section branch circuit wiring, terminated in fittings and consumer units that were designed for copper and that do not accommodate the greater movement and oxidation of aluminium connections over time. The practical manifestations of this risk include discolouration or charring at socket outlets, switch faceplates, and consumer unit terminals, burning smells from switch and socket positions, and in severe cases, fire originating at a poorly connected aluminium terminal. Prestige Engineers assess aluminium wiring installations in London properties and provide remediation recommendations ranging from terminal treatment and replacement of outlets to partial or full rewiring, depending on the condition and extent of the installation.