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• Aluminum Electrical Service Cables, Electrical Panel Components & Wiring
• How to determine the size, capacity, or ampacity of electrical service at a building

This article summarizes possible safety and functional concerns with the use of aluminum wiring for service entry cables or electrical panel components in buildings, and provides a link to the aluminum wiring information website. This is a chapter of our discussion of the inspection of electrical services at buildings in order to determine service capacity in volts and amps. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

ALUMINUM SECs & WIRING - Aluminum Service Cables and Wiring in Buildings for Electrical Service Delivery

In both branch circuit and entrance cable wires, the permitted wire gauges for copper are normally one size smaller than for aluminum used at the same ampacity rating. This is because copper is a better conductor than aluminum. Aluminum wire must be larger to safely carry the same current as copper.

Fire and Safety Issues with Aluminum Electrical Wiring

There are important fire safety issues concerning the presence of aluminum branch circuit wiring in buildings - not discussed in this article. Solid aluminum branch conductors are no longer used in new wiring.

Aluminum service entrance cables and aluminum single-purpose high-amperage circuits [NOTE: Such as for auxiliary sub-panels, central air conditioning or electric ranges.> are commonly installed in many communities.

Many new electric service panels use plated aluminum parts. According to some experts risks remain even with these permitted applications in both the US [see "Reducing the Fire Hazard in Aluminum-Wired Homes," Jesse Aronstein, Ph.D., Wright Malta Corporation, Ballston Spa, NY, 1982] and Canada [see "Overheating Failures of Aluminum-Wired Special Service Connectors," Jesse Aronstein and Wilfred E. Campbell, IEEE Transactions on Components, Hybrids, and Manufacturing Technology, Vol. 4 CHMT-6, No.1, March 1983.] The risks of poor connections and fire hazards for aluminum SEC wiring are reduced by proper abrasion of the connected wires, proper tightening of the connector, and use of a special anti-corrosion flux compound.

As recently as June 2006 we received a report of a major house fire which the owner asserts began at an overheating electrical service entry cable connector. Our opinion is that because the number of these connections is less than on a branch circuit wire, and possibly for other technical reasons involving the performance of multi-stranded aluminum wire, the risk of a fire is probably statistically less than with solid conductor branch circuits. It would appear that the risk is not as low as with copper service entry cables.

Key References on Aluminum Electrical Wiring

The Aluminum Wiring Information Website for a thorough discussion of aluminum branch circuit wiring concerns in the U.S. and in Canada as well. [There is disagreement among professionals about the Canadian risk and failure rate. Ontario Hydro and some Canadian inspection professionals do not acknowledge a significant risk from aluminum wiring in Canada. However the Scarboro development in Ontario demonstrated that failures and fires have occurred in that country.--DF]

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Technical Reviewers

• The Original Authors: Alan Carson is an ASHI Member, national home inspection educator, author and building failures researcher in Toronto, Ontario. Daniel Friedman, an original author of this article and the editor and producer of InspectAPedia where this article now appears is an ASHI Member, first ASHI Technical Committee chairman, editor and publisher of the ASHI Technical Journal, licensed home inspector, educator, and building failures researcher in Poughkeepsie, NY. Robert Klewitz is a licensed professional engineer, a professional home inspector, an ASHI Member, and has served on the ASHI Technical Committee as well as in other ASHI activities. His practice is in Issaquah, WA.
• Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
• Douglas Hansen, Robert Stead. Mark Cramer. Photographs: Daniel Friedman.
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
• N. Srinivasan, MSEE, is a senior member of IEEE with 30 years experience in the electrical industry. Mr. Srinivasan is in Vienna VA.
• Louis P. Babin generously contributed technical editing about the effects of doubling ampacity in an electrical circuit (September 2007)

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More expert information on Inspecting Electrical Equipment and Electrical Safety for Inspectors

More Information on Electrical Inspections & Building Diagnostic Inspections and Repairs

• * Safety Hazards and Safe Inspection Procedures for Electrical and Home Inspectors at Residential Electric Panels
• Aluminum Wiring Information Website Aluminum Electrical Wiring Hazards and Repairs: in-depth authoritative info, photos, documents including selection of proper vs. ineffective repair methods. E.g.: Ideal 65 "Twister" purple connector fails in field and lab testing with aluminum wire.
• Ampacity of an Electrical Service: How to Estimate the electrical service size or ampacity entering a building
• Circuit Breaker, a bad one fails to trip failure at aluminum bus-to-circuit breaker connection - field report and photographs
• Electrical Panels, How to Inspect in Buildings, safety for electrical inspectors, electrical panel, fusing, wiring defects, defective products. Inspection Class Presentation
• Federal Pacific Electric (FPE) Stab-Lok Circuit Breaker Panel Hazards Website - Latent fire hazards, in-depth authoritative research, documents, advice on Stab-Lok electric panel and circuit breaker failures and what to do when this equipment is found in buildings.
• Lightning Strike Risk Assessment, Protection Systems & Services
• Multi-wire branch circuit inspection and defects
• "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
• "Simplified Electrical Wiring," Sears, Roebuck and Co., 15705 (F5428) Rev. 4-77 1977 [Lots of sketches of older-type service panels.]
• "How to plan and install electric wiring for homes, farms, garages, shops," Montgomery Ward Co., 83-850.
• Rust and Corrosion in Electrical Panels, A Study and Report on Frequency and Cause for Electrical and Home Inspectors at Residential Electric Panels


• Electrical System & Wiring Hazard Inspection, Detection, Cause, Remedy, Prevention - Main Electrical Page
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