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ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR
ALUMINUM WIRING HAZARDS & REPAIRS
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Aluminum wire connections can overheat enough to start a fire without ever drawing enough current to trip a circuit breaker. Other products sold for repair of aluminum wiring connections: Scotchlok 3M™, Ideal 65™ Purple "Twister", Marrette B-Cap ACS™ #63 AL/CU Twist-On Connector, Electrical Receptacles and switches marked "COALR" or CU/AL, and Harbor Freight's Aluminum to Copper Crimping Tool are not recommended. Caution - some of these products are not recommended or have been superceded by newer listed products. This website answers nearly all questions about aluminum wiring inspection, hazards, repairs
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OTHER Not-Recommended ALUMINUM WIRING REPAIR PRODUCTS: for Aluminum Electrical Wiring - Ideal 65 Purple Twister and Other Aluminum Wire Products/Articles
Currently-recommended aluminum wiring repair products & methods such as the AMP/TYCO COPALUM TM crimp connector and the AlumiConn TM connector, as well as other aluminum wire repair methods can be read-about at ALUMINUM WIRING RISK Reduction.
Aluminum Wiring Connectors or "repair methods" which are obsolete or which are not recommended, such as the COALR or CU/AL devivces, the now obsolete Scotchlok TM 3M Special Method, and aluminum wiring connectors and repair methods such as the Ideal-65 TM Purple Twist On Connector, or conventional twist-on wire connectors are described just below. Further details are also found at Aluminum Wiring Repair Methods - CPSC Meeting.
The photograph shows a back-wired electrical receptacle with an aluminum-wired branch circuit. In this photograph case the electrical receptacle was marked as "AL-CU" but was further marked as Backwire CU-ONLY by its manufacturer.
[Photograph courtesy of Roger Hankey. Contributions of photos of CU-AL and COALR receptacles are sought by the author.].
Harbor Freight offers a hydraulic crimping tool advertised as usable for aluminum wiring repairs. The tool is displayed and sold only by Harbor Freight as the Hydraulic Wire Crimping Tool Model 66150. Harbor Freight is a large, long-established tool retailer (since 1978) retailing a wide variety of tools and equipment.
We recommend that you read the instruction manual for this tool (large PDF).
As of 7 Feb 2009 we don't know the approval status of this tool for aluminum wiring repairs.
We took a preliminary look at the Harbor Freight Hydraulic Wire Crimping Tool Model 66150 and also at the instruction manual, and we saw that HF advertises that this tool intended for connecting copper and aluminum wires. The text does not say that the tool is approved for joining copper to aluminum wires as is performed in the standard aluminum wiring repair procedure. But we may be interpreting the manufacturer's text more carefully than did their ad copy writer.
What we don't yet know about this aluminum or copper wire crimping tool:
What we have learned so far about this copper to aluminum wire crimping tool
The Harbor Freight Hydraulic Wire Crimping Tool Model 66150 instruction manual has some interesting paragraphs like
That paragraph alone might exclude the use of this tool for aluminum-copper pigtailing repairs. There are no such instructions. The manual also, quite understandably, includes a general disclaimer:
Is the Harbor Freight hydraulic crimping tool for copper and aluminum wires recommended for repairing aluminum wiring?
But given the difficulty people in some areas have finding qualified aluminum wiring repair electricians, connectors, and tools, here some
THEN having another aluminum wire repair method would be a boon for the AL wire repair topic.
This tool is Distributed exclusively by Harbor Freight Tools®. 3491 Mission Oaks Blvd., Camarillo, CA 93011
Until those safety conditions are met we do not recommend any aluminum wire repair method other than those described at ALUMINUM WIRING REPAIR METHODS. Using a non-recommended tool for repairing aluminum electrical wiring might be unsafe and might also create fire insurance issues with your carrier.
On 3/6/14 we again asked the company for clarification, including an explanation of this concern:
Ideal-65 Purple Twist On Connector the Ideal 65 Twister (don't call it a "wire nut") - this one doesn't work - purple twist-on connector sold for aluminum wire repair
CPSC reiterates unsuitability of twist-on connectors (Including the Ideal No. 65) for repairing aluminum wiring in residences.
Ideal 65 "Twister" History of and Links to CPSC Documents about Purple Twist-on connector failures
Ideal Industries, Inc., 1000 Park Ave, Sycamore IL 60178-994. 800-435-0705 U.S. or 800-527-9105 Canada email@example.com
Note: The instructions for this connector require that it always include a copper pigtail when making aluminum wiring connections - a condition impractical for splicing aluminum-to-aluminum wires.
Dr. Jesse Aronstein, "Evaluation of a Twist-on Connector for Aluminum Wire", Forty-Third IEEE Holm Conference on Electrical Contacts, Jan 1997, 0-7803-3968-1/97.
Marrette B-Cap ACS#63 AL/CU Twist-On Connector for aluminum wire repair - is also not recommended for aluminum wire repair by the pigtailing approach. Dr. J. Aronstein provided this answer to the question that we have been asked, "Can I use the Marrette B-Cap ACS 63 AL/Cu twist-on connector along with antioxidant for reliable copper-to-aluminum pigtailing repair of aluminum electrical wiring?"
A paper was published on those tests and is our first citation just below. Aronstein comments that "The addition of an inhibitor compound does not correct the underlying deficiency of the twist-on connector type when used with aluminum wire." See "Reducing the Fire Hazard in Aluminum-Wired Homes" for additional information on twist-on connectors with aluminum wire. -- Jesse Aronstein, Ph.D., P.E.
Scotchlok 3M Special Method [- superceded by new alternate repair as of June 2007 -]: this ""Scotchlok 3M Special Method was previously recommended as independent tests showed that it performed acceptably.
While this repair method has been superceded by new alternate repair methods as of June 2007, we have kept this description available to aid home buyers, electricians and home inspectors who may discover or need to be able to recognize this aluminum wire repair method if it was previously used in the building.
Suggested citation for this web page
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The link just above provides access to Reducing the Fire Hazards in Aluminum-Wired Homes, by Dr. Jess Aronstein, Ph.D., This document answers most technical questions about the hazards and remedies of aluminum electrical wiring. An easy to print form of this guide in PDF form is also provided free at ALUMINUM-WIRED HOMES, REDUCE THE HAZARD [PDF].
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