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Independent Field Failure Investigation & Test Lab Results Indicate that Twist-On Connectors for Aluminum Wiring Repairs Do Not Perform Acceptably as a Repair for Residential Aluminum Wiring

• "Analysis of field failures of aluminum-copper pigtail splices madewith twist-on connectors", Aronstein, J.
  Poughkeepsie, NY, USA; Electrical Contacts, 1999, Proceedings of the Forty-Fifth IEEE Holm Conference, reports on a study of failures among 4,531 connectors used in 102 apartments within one year of installation using normal, proper workmanship and typical aluminum branch circuit wiring and concludes that the connector is not suitable for permanent use with aluminum wire residential wiring systems. Abstract and source are provided below.
• Splices made with the Ideal-65 Twister™ connector are not capable of long-term safe performance as part as part of the permanent wiring of existing aluminum wired homes. The results of independent testing were presented at the IEEE Holm Conference on Electric Contact Phenomena in Philadelphia Oct.20 1997. Abstract and source are provided below.
• Documents provided under the Freedom of Information Act, describe independent testing of the Ideal 65 "Twister" purple twist-on connector marketed for certain retrofit repairs of aluminum electrical wiring. Abstract and sources are provided below.

Here are photos of failed Ideal-65™ twist-on connectors currently sold for aluminum wire "repair," submitted by Dr. Jess Aronstein on 1-10-01.

Documents on the Ideal 65 Purple Twister™ Twist-on Connector for Aluminum Wiring Repairs

Documents (listed below) indicate that notwithstanding it's UL Listing, the purple Ideal #65 "does not meet the UL486C heat-cycle test performance requirements when tested with splices representative of the common "pigtailing" combination used in aluminum-wired homes, even though the connector is UL listed for those wire combinations."

The UL response refers-to but does not address Aronstein's findings.

• Letter, 1/4/96, Aronstein to Castino at Underwriters Labs
• Letter, 3/29/96, Aronstein to Castino at Underwriters Labs
• Letter, 3/29/96, Aronstein to King at US Consumer Product Safety Commission
• Letter, 4/22/96, Castino to Aronstein (independent tester)

"Analysis of field failures of aluminum-copper pigtail splices madewith twist-on connectors", Aronstein, J.
Poughkeepsie, NY, USA; Electrical Contacts, 1999, Proceedings of the Forty-Fifth IEEE Holm Conference on
Publication Date: 1999, page(s): 87-93, Meeting Date: 10/04/1999 - 10/06/1999, Location: Pittsburgh, PA, USA
ISBN: 0-7803-5549-0, References Cited: 15, INSPEC Accession Number: 6520589
Digital Object Identifier: 10.1109/HOLM.1999.795931 Current Version Published: 2002-08-06
Available from IEEE

Abstract: A new type of twist-on splicing connector for use with aluminum and copper wire combinations was utilized to reconnect wire terminations in a group of residential apartment units. The connector differs from conventional twist-on connectors in that it is pre-filled with a corrosion inhibitor compound containing suspended particulates. Burnout occurring among these splices led to removal and replacement of all of the new connectors.

In this study, the connectors removed from 102 apartments were inspected for signs of overheating and for indications of abnormal conditions that might cause the failed connectors included samples that were applied to rated wire combinations and showed no sign of abnormal installation or application conditions.

Tests of the aluminum conductors from the apartments reveal no abnormalities that could account for the poor performance of the new connector. The inhibitor compound inside the connector was determined to be of limited effectiveness in improving the wire-to-wire contact through the high resistance film on the aluminum wire surface. On the basis of the field failures in combination with previously reported laboratory studies it is concluded that the connector is not suitable for permanent use with aluminum wire residential wiring systems

Comments: In 1997 a licensed electrician was contracted to replace all aluminum branch wiring in a 1968 residential apartment building used CO/ALR type devices to replace existing devices; the electrician "pigtailed" (aluminum spliced to copper conductor pigtails) heavily loaded branch circuits using a recently-introduced twist-on connector rated for that purpose. Independent testing (see Evaluation of a Twist-on Connector for Aluminum Wire", J. Aronstein, below) had previously demonstrated significant weaknesses of this connector. Other aluminum to copper splices using this connector involved connections to copper wire leads of lighting fixtures, HVAC equipment, and appliances.

Electrical failures were noted within the first year after these repairs had been made, detected by smell or device malfunction. Infra-red temperature measurements showed abnormal heating of other splices. By the end onf 1998 these conditions had led to replacement of all of the newly-made twist-on splices, this time using the COPALUM connector recommended by the US CPSC for this application. During replacement, additional examples of overheating were discovered.

All of the 4,531 removed connectors that had been installed in 102 apartments were retained and provided to Dr. Aronstein for further study. The results were pubished in the 1999 IEEE paper cited above. Aronstein did not find evidence of improper installation of the devices, and study of the aluminum wire itself for abnormalities (such as abnormal levels of oxide film on wire surfaces leading to higher wire-to-wire resistance in the splices) did not find that abnormal wire conditions were a factor in the failures.

These studies left the failures to be attributed to the devices themselves, by components and mechanisms within the device as Aronstein explains in detail in the paper. This article describes the field results and testing of a twist on connector produced by Ideal Industries, Ideal#65 purple "Twister"™ twist-on connector listed and sold as a repair/retrofit for residential aluminum wiring.

"Evaluation of a twist-on connector for aluminum wire", Aronstein, J., Poughkeepsie, NY, USA;
Electrical Contacts, 1997., Proceedings of the Forty-Third IEEE Holm Conference on Publication Date: 20-22 Oct 1997
On page(s): 46-56, Meeting Date: 10/20/1997 - 10/22/1997, Location: Philadelphia, PA, USA
ISBN: 0-7803-3968-1, References Cited: 21, INSPEC Accession Number: 5795024
Digital Object Identifier: 10.1109/HOLM.1997.637874 Current Version Published: 2002-08-06,
Available from IEEE

Abstract: A new type of twist-on splicing connector for use with aluminum and copper wire combinations is tested to determine initial resistance, performance in a zero-current environmental 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 into 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, and is not considered to be suitable for permanent splices in residential aluminum wire applications

This article describes the field results and testing of a twist on connector produced by Ideal Industries, Ideal#65 purple "Twister" twist-on connector listed and sold as a repair/retrofit for residential aluminum wiring.

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