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Aluminum wiring repair failures at copper pigtail connections: Illustrations, photos, and explanation of overheating and failures at copper pigtail connections used to repair aluminum wire. In this article series aluminum electrical wire twist-on connector failures and repair procedures are described,
including aluminum wire repair methods which work and methods which do not work and are unsafe.
Aluminum Wiring Repair Failures due to overheating at copper pigtails using twist on connectors
Color photos of aluminum wire repair procedures, and photos of failed connectors are included.
This document series describes hazards with existing aluminum wiring repair products, explains the aluminum wiring failure mechanism,
and reviews recommended retrofit procedures including use of readily-available materials.
This information was presented to the US Consumer Product Safety Commission by Dr. J. Aronstein, 9/28/95.
The minutes of that meeting were obtained under the Freedom of Information Act and posted by Daniel Friedman January 1996.
Click any image to see an enlarged version.
4. Burnouts like this occurred when various UL-listed twist-on connectors were tested for the pigtailing application, installed as per the manufacturers' instructions. Poor test results for twist-on
splices with aluminum wire were reported by UL, Battelle, CPSC, and various wire and device manufacturers.
5. The fire hazard posed by these splices when they fail is easily seen when the "burnouts" are observed while passing current. At about 17 amps, less than the 20 Amp rating of the (#10 aluminum wire)
circuit, the connector spring is red hot. The voltage drop is about 2 volts, so downstream loads operate normally.
6. Additional red-hot twist-on connector splices fr6m the CPSC tests are shown here. The key point is that a significant percentage of the CPSC test splices over a period of several years failed in
this hazardous manner, the spring becoming red hot. The connector shells ignited (smoldering combustion).
7. These tests were all conducted within rated service conditions. Applied current never exceeded 90% of the circuit rating
(based on aluminum wire size used). The twist-on connectors used were UL listed for the application, and were installed as per the manufacturers instructions.
Aluminum Wiring Repair Failure Photos & Causes: overheating at copper pigtails using twist on connectors
8. Simpler splices also failed. Here is a basic splice with two aluminum wires. Overheating is evident in the discoloration band around the shell. This is a characteristic heating pattern for failing
aluminum wire twist-on splices. With time, further degradation occurs, and fire hazard develops with current loading.
9. The characteristic burn pattern is an important clue toward understanding the failure mechanism of the aluminum-wired twist-on connector splices.
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"Repairing Aluminum Wiring", US CPSC Publication 516, U.S. Consumer Product Safety Commission, Bethe3sda MD, website: www.cpsc.gov / www.SaferProducts.gov, updated June 2011, original source: .cpsc.gov/cpscpub/pubs/516.pdf, Quoting:
The U.S. Consumer Product Safety Commission (CPSC) staff and other government
have investigated numerous hazardous incidents and fires throughout the nation
involving aluminum branch circuit wiring. A national survey conducted by Franklin
Institute for CPSC showed that homes built before 1972, and wired with
are 55 times more likely to have one or more wire connections at outlets reach
“Fire Hazard Conditions”1 than homes wired with copper. That survey encompassed only
the wire connections at outlets. It did not address other types of aluminum wire connections
and splices in homes that are also prone to fail. No information was developed for
aluminum-wired homes built after 1972.
The fire hazard investigated by CPSC occurs at connections with aluminum wire, including
receptacles or switches and junction boxes; or the hazards occur with major appliances,
including dishwashers or furnaces, for example. There are several deterioration processes in
aluminum wire connections that cause increased resistance to the flow of electric current,
resulting in damage that is cumulative in effect. That increased resistance causes overheating,
sometimes at hazardous levels, when current is flowing in the circuit.
"Repairing Aluminum Wiring," [Original, now obsolete] U.S. Consumer Product Safety Commission Publication CPSC#516 available online
"Record of Commission Action, Commissioners Voting by Ballot", CPSC Publication No. 516, Repairing Aluminum Wiring (original version op.cit.), (Briefing package dated March 15, 2011), Quoting: The Commission voted unanimously (5-0)·to approve republication of CPSC Publication No. 516, Repairing Aluminum Wiring, with the explicit recognition that the COPALUM and AlumiConn connectors currently are the only products that meet the agency's standards to prevent aluminum wire fire hazards Copy on file as /aluminum/Pub516_Alumi_Conn.pdf
Dr. Jess Aronstein, firstname.lastname@example.org is a research consultant and an electrical engineer in Schenectady, NY. Dr. Aronstein provides forensic engineering services and independent laboratory testing for various agencies. Dr. Aronstein has published widely on and has designed and conducted tests on aluminum wiring failures, Federal Pacific Stab-Lok electrical equipment, and numerous electrical products and hazards. See Aluminum Wiring Bibliography and see FPE HAZARD ARTICLES, STUDIES for examples.
"The Influence of Corrosion Inhibitor and Surface Abrasion on the Failure of Aluminum-Wired Twist-on Connections",
Aronstein, J.; Campbell, W.,
Components, Hybrids, and Manufacturing Technology, IEEE Transactions on
Volume 7, Issue 1, Mar 1984 Page(s): 20 - 24
"Overheating Failures of Aluminum-Wired Special Service Connectors", J.Aronstein and W.E.Campbell,
IEEE Transactions, Vol. CHMT-6, No. 1, March 1983.
This paper appears in: Components, Hybrids, and Manufacturing Technology, IEEE Transactions on
Publication Date: Mar 1983
Volume: 6, Issue: 1
On page(s): 8 - 15
Current Version Published: 2003-01-06. This paper is available to IEEE members and subscribers and can be obtained through public or academic libraries.
Abstract: Special service" twist-on connectors are tested with aluminum and copper wire combinations. The special service connectors are qualified by a Canadian standard which applies to connectors for use with aluminum branch circuit conductors. Two brands of special service connectors are presently qualified by this standard and marketed. Both are rated for various combinations of aluminum and copper conductors. Samples of both brands are tested in this investigation. The tests are conducted within rated electrical and environmental conditions, with connections made according to the connector manufacturers' instructions. Overheating failures have occurred among the aluminum-wired special service connector combinations. The failures are accelerated by humid environment to a greater extent than by the application of electrical current. In contrast, connections which are copper-wired, using either standard or special service connectors, are stable and failure-free. The difference between the standard twist-on connectors and the special service connectors is in the material used for the connector spring. Improved compatibility between the spring material and the aluminum conductor, compared to the plated steel springs of the conventional twist on connectors, has not dealt with several important failure mechanisms. The test results indicate that the new standard, as presently defined, cannot be relied on to screen out aluminum-wired connector combinations which will not survive long-term operation within rated conditions. Thus the objective of accelerated qualification testing-- the prediction and assurance of safe and reliable operation in actual service---is not achieved in this case. The reasons are discussed, along with possible improvements.
"Evaluation of a Twist-on Connector for Aluminum Wire", Dr. Jesse Aronstein, Forty-Third IEEE Holm Conference on Electrical Contacts, Jan 1997, 0-7803-3968-1/97.
[This article describes the Ideal Industries Ideal#65 purple "Twister" twist-on connector marketed as a repair/retrofit for residential aluminum wiring.--DJF]
Abstract: A new type of twist-on splicing component for use with aluminum
and copper wire combinations is tested to determine initial resistance, performance in a zero-current environment test, performance in a heat-cycle test, and portion of current carried by the connector's steel spring. The splices tested consist of two aluminum wires and one copper wire.
The aluminum wire samples used for the test are of the types actually installed in aluminum-wired homes. Initial resistance is found to be relatively high,
and there is a significant sample-to-sample variation. This reflects failure to consistently establish low-resistance wire-to-wire contact through the insulating oxide film on the wire. Results of the environmental and heat-cycle tests show deterioration of a significant portion of the samples.
The splices made with this connector are also found to be sensitive to mechanical disturbance, such as applied in
normal installation when the completed splice is pushed back in to the junction box. Based on the test results, it is concluded that this connector has not overcome the fundamental deficiency of twist-on connectors for use with aluminum wire applications. Keywords: aluminum wire, connectors, twist-on connectors, environmental test, heat-cycle test.
Thomas & Betts, 8155 T&B Boulevard Memphis, TN 38125 USA, is a producer of more than 30,000 electrical components. 888-862-3289. Quoting the company: Thomas & Betts offers more than 30,000 high-quality products marketed under a variety of market-leading brand names. Designed to help passively conduct electricity, Thomas & Betts products are found everywhere electricity is used -- inside commercial and industrial buildings, in homes and schools, inside complex machinery and original equipment, in the power generating plant and distribution network, outside your home and underground.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
ALUMINUM WIRE REPAIR METHODS to reduce risk in buildings with Aluminum Electrical Wiring - Overview of Acceptable Repair Practices (in the document you are presently viewing)
Aluminum Wire Repair Method Details - "How to" details, how to identify, COPALUM repair, alternative repairs, history, products, research, source of special AMP TYCO COPALUM connectors & COPALUM Electricians (in the document you are presently viewing)
COPALUM Electricians: Sources of TYCO COPALUM -Certified/Trained Aluminum Wire Repair Services (in the document you are presently viewing)
Other Products, Ideal 65 Purple Twister (not recommended), & other Aluminum Wire Products/Articles (in the document you are presently viewing)
Reducing the Fire Hazards in Aluminum-Wired Homes, Jess Aronstein, Ph.D., This document answers most technical questions about the hazards and remedies of aluminum electrical wiring. Some of the sections of this very thorough document are listed below: