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Overheating aluminum electrical wires starting a fire (C) InspectApedia.com Jess Aronstein Aluminum Wiring Hazard & Repair Procedures
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  • POST a QUESTION or COMMENT about aluminum electrical wiring: hazards, risks, proper repairs, identifying aluminum wiring. Questions and Answers about Aluminum Wiring Hazards, Failures, Failure Cause, & Aluminum Wiring Repairs

We answer just about any question concerning aluminum electrical wiring, aluminum wiring failure causes, cures, repairs, and prevention.

We include authoritative, expert aluminum wiring failure research, field failure reports, and descriptions of approved aluminum wiring repair procedures and products.

At page top, an illustration from a research report by Dr. Jess Aronstein illustrates how aluminum wire electrical connections overheat to start a fire. At the point shown in Aronstein's photograph, the twist-on connector is completely burned but the electrical fire continues, having ignited the plastic jacket of the wire insulation and the cable jacket end.

In the wall of an actual building, this fire may spread outside of the electrical box, or it may not, depending on the actual environment and what combustible materials are close to the electrical box. Aronstein concludes that in any event, the inside of an electrical box in a building is no place for burning materials.

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Aluminum Electrical Wiring Dangers, History, & Repair Procedures

Photograph of overheating aluminum-wired electrical outlet

This website describes the hazards and remedies for aluminum electrical wiring - a fire hazard in homes. We provide complete and authoritative research, technical information, description and explanation of why solid conductor branch circuit wiring of aluminum is unsafe, and we describe both proper and improper repair methods for aluminum electrical wiring.

Watch out: unless it has been repaired properly, solid-conductor aluminum electrical wiring, installed in homes in North America in the 1960's and 70's is a fire hazard in buildings. Aluminum electrical wire was never "recalled" in the U.S. nor in Canada. The absence of a product recall is not an assurance that it is safe.

Aluminum electrical wiring is indeed "safe" in buildings if it has been properly repaired using methods and connectors described at this website.

[Click to enlarge any image]

Just how safe is un-repaired aluminum wiring? According to the U.S. Consumer Product Safety Commission, fires and even deaths have been reported to have been caused by this hazard.

Mis-information about aluminum wiring is widespread and its failure mechanism leading to overheating is usually not explained properly.

Problems due to aluminum wiring expansion, or much more likely micro-fretting and arcing at the aluminum wiring connectors, can cause overheating at the connections between the wire and devices (switches and outlets) or at aluminum wire splices.

The connections can become hot enough to start a fire without ever tripping a circuit breaker!

The photos shown at left and just below are not the most dramatic catastrophes linked to fires caused by aluminum wiring. But these are conditions that are found in many homes with aluminum wiring, confirming that this is a real, common, and widespread hazard.

Photograph of overheating aluminum-wired electrical outlet

CPSC research shows that "homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach "Fire Hazard Conditions" than are homes wired with copper.

"Post 1972" aluminum wire is also a concern. Introduction of the aluminum wire "alloys" in 1972 time frame did not solve most of the connection failure problems.

Aluminum wiring is still permitted and used for certain applications, including residential service entrance wiring and single-purpose higher amperage circuits such as 240V air conditioning or electric range circuits.

The fire risk from single purpose circuits is much less than for branch circuits.

But it's not necessarily because of a "new alloy" as some folks assert. It's because there are enormously fewer connections (four or six rather than 30 or 40 per circuit) and thus statistically a smaller chance of a connection failure. These connections do still burn up, as indicated by field reports.

List of Key Articles on Aluminum Wiring Hazards & Repair Methods

Photos below show an improper aluminum-to-copper pigtail splice which is overheating, and an infra-red photo of the same connection, from a more distant view (courtesy of G. Cohen). Aluminum wire connections can overheat enough to start a fire without ever drawing enough current to trip a circuit breaker.

Photograph of this overheating and improperly-made aluminum to copper pigtail splice. Photograph of this overheating and improperly-made aluminum to copper pigtail splice.

The AMP TYCO COPALUM Connector for Aluminum Wiring Pigtailing Repairs

Photo of the AMP COPALUM aluminum wiring connector recommended by the US CPSC

AMP TYCO COPALUM Copper-to-Aluminum Pigtailing Use the special AMP (now TYCO) COPALUM high pressure crimp connector and special tool to connect short copper wires to every aluminum wire end in the building, reconnecting the copper to the various devices (outlets, switches, lights) and splices.

The AMP (originally TYCO) COPALUM connector method is described is described in detail

at PIGTAILING USING AMP "COPALUM" CONNECTORS.

COPALUM ALUMINUM WIRING CONNECTOR AVAILABILITY discusses how to get these aluminum wire connectors

The AlumiConn™ Aluminum Wiring Connector for Pigtailing and Repairs

Photo of the AlumiConn aluminum wire lug connector sold by King Innovations

AlumiConn TM Purple #95135 aluminum to copper lug connectors [New in 2006, U.L. Listed, 2007 completed independent testing] available from King Innovation.

The AlumiConn connector is now recommended for aluminum wiring repairs - US CPSC.

Results of independent testing indicate that this product "... is predicted to have a high probability of failure-free long-term safe performance, PROVIDED THAT THE SETSCREWS ARE CAREFULLY TIGHTENED TO THE MANUFACTURER'S RECOMMENDATION".

Alumi-Conn where to buy, how to install: 

Obsolete Aluminum Wiring Repair Method - No Longer Recommended

Photo of the 3M Scotchlok wiring connector which can be used for aluminum wiring repairs, has tested successfully but has not been recommended by the US CPSC

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 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.

A summary of this method is at Scotchlok 3M CONNECTOR and

details of this method are at SCOTCHLOK 3M REPAIR CONNECTORS repair method.

Other Aluminum Wiring Repair Methods that Are Not Recommended

Photo of the Ideal 65 purple twister aluminum wire connector which is NOT RECOMMENDED

Other methods - not recommended: Warnings regarding other "repair" methods which are not recommended are discussed

at ALUMINUM WIRING REPAIR, Other Products,

such as the Ideal 65 purple "Twister" connector shown in the photo at left (12 connectors cost $49. to $79.), Marrette B-Cap ACS™ #63 AL/CU Twist-On Connectors, and electrical receptacles and outlets marked "COALR" (even if these worked, which has not been demonstrated, what about all of the other electrical connections and splices in the building?) and others.

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-11-07 by Bob D. - replace all aluminum wiring after storm damage & flooding

My home was built in early 1970s and has aluminum wiring. Our home was damaged in a hurricane which ripped the roof decking off the rear of our home. Due to the amount of water and wind that entered our home our electrician has recommended we remove all aluminum wiring.

I’m not sure who to turn too so I know everything is being replaced correctly. Thanks

On 2022-11-07 by InspectApedia (Editor) - how do I repair damaged wiring from hurricane

@Bob D.,

I think there are probably several issues here. Naturally I can't assess by text whether you're wiring itself was actually water damaged but I'm sure you've read by now that aluminum wiring is a fire hazard. The hazard occurs at the connections.

There is an approved repair method using one of two specific connectors to install copper pigtails at each connection. So unless there's some evidence that the wiring itself is damaged and unsafe the connection repair approach should be considerably less costly.

Ask for specifics about what sort of damage was seen and let me know. It would be helpful to see some photos of conditions, one per comment and as many comments and photos as you like.

I think part of the problem is that the electrician may be nervous about working on your wiring because of a concern for liability.

On 2022-11-07 by Bob D. - structural engineer gives bad news to replace all trusses

@InspectApedia (Editor), Hi. Thanks so much for the information. Today i finally had a structural engineer come out and give me the bad news that he recommends that all of the trusses in the house be replaced. So it seems like everything will be demo'ed and replaced. Thanks again for your help.

On 2022-11-07 by InspectApedia (Editor)

@Bob D.,

By separate private email you wrote:

My home was severely damaged from Hurricane IAN. The roof decking was torn off across the whole back of my home. Which caused the ceiling to come down in 4 rooms. There was also water on all floors in all rooms.

Our home has aluminum wiring and our electrician has recommended to remove it all and replace with copper not just because of damaged wiring but water damage to aluminum. The electrician and general contractor both said I should get an inspection for structural issues. Are there engineers that can inspect all components of your home, or should I get folks who are specialized in a particular area. Thanks in advance for any help.

We replied:

Structural questions can be addressed by an engineer who is trained in structural or civil engineering. Most Engineers are not expert in the details of building electrical and mechanical and other subsystems.

An experienced home inspector who is willing to examine storm damage to buildings may not be qualified to assess structural damage but should be capable of giving you a general idea of the scope of work that's necessary on your building across all of its systems.

Be sure to read

FLOOD REPAIR PRIORITY STEPS

ELECTRICAL SAFETY for FLOOD DAMAGE INSPECTORS

FLOOD REPAIR CONTRACTORS

About your electrical wiring, independent of the alumnum,

In any home, electrical wiring that has been under water is unsafe until it has been inspected and perhaps had several types of components replaced. For example even if plastic-covered wiring itself appears un-damaged, electrical connections, splices, junction boxes, electrical receptacles, light switches have been wet and are at risk of corrosion.

On 2022-04-03 by Robert Ketcheson - use antioxidant paste and a twist on connector for aluminum wire repair?

What about coating the aluminum wires & copper wires with anti-ox agent before twisting together under a traditional Marette?

I had heard from an electrician that this will prevent oxidization on the wires and will neutralize any heat discrepancy between the two conductors. Is this not correct?

On 2022-04-03 by InspectApedia (Editor) - don't use twist on connectors with antioxidant for an aluminum wiring pigtailing repair

@Robert Ketcheson,

Thank you for the question about using a particular brand of twist on connectors with antioxidant for an aluminum wiring pigtailing repair.

You will find that option described in detail in this article series.

And you will read that simply cutting the wires and using antioxidant combined with a twist on connector is not safe and leads to overheating and fires.

Even simply looking at the photographs on this page you will see that part of the problem is that the current is flowing through the spring of the connector rather than from wire-to-wire. As a result the device overheats, melts, and invites building fire.

There was a procedure that involved a much more complicated process in which the wires were stripped, coated with antioxidant, and then abraded or sanded through the antioxidant, however the researcher that who did that work finds that the current approved connectors for aluminum wiring are safer and much less complex and will perform better.

Watch out: Bottom line don't do what you suggested. Using twist on connectors for aluminum wiring repair is unsafe, is not recommended by the US CPSC, and may also cause you to lose your fire insurance coverage.

Use one of the two approved aluminum to copper pigtail and connectors.

On 2021-02-24 by Travis - Why can't 2-2-2-4 SER aluminum wire be run in conduit, unerground?

Why can't 2-2-2-4 SER aluminum wire be run in conduit, unerground?

On 2021-02-24 by danjoefriedman (mod)

@Travis, this sounds like one of those unanswerable questions like "are you still beating your wife?"

Your question contains a false premise.

There are in fact aluminum service entrance cables that are rated for underground use. For example

2-2-2-4 Dyke Quadruplex Aluminum Conductor Underground Direct Burial 600V URD

On 2020-12-18 by John - Is copper clad aluminum safe?

Is copper clad aluminum safe

On 2020-12-18 by danjoefriedman (mod) - copper clad aluminum safety

John

thank you for helpful question about the safety of copper clad aluminum wiring.

YES - All of the sources that we have reviewed and experts whom we've consulted agree the copper clad aluminum wiring performs about as well as copper wiring. It doesn't have the same connection, arcing, corrosion, overheating issues as those aluminum wire.

Obviously I can't say a thing about the safety of your particular wiring installation because safety depends on so many other installation details. But the wire itself has been found to perform correctly and safely.

On 2019-12-27 by Deborah Haney - safe to use new high wattage appliance on an aluminum-wired circuit?

I have been given a new cooking appliance that is rated power of 1200 watts. It is a compact oil-less fryer, that I am wondering if it is safe to use in an aluminum wired mobile home. Does anyone have a qualified answer?

On 2019-12-27 by danjoefriedman (mod) - NO electrical device is safe in an aluminum wired home

Deborah

Thanks for asking an important aluminum wire safety question.

Frankly, NO electrical device and NO connections in an aluminum wired home are "safe" and there is a serious fire risk unless the wiring has been properly repaired using one of the two methods recommended by the US CPSC: the AMP COPALUM crimp connector pigtailing copper to the original aluminum at every single connection throughout the home, or the AlumiConn connector similarly installed.

And yes, using a higher wattage appliance may increase the risk of overheating and a fire.

I'm not sure what constitutes a "qualified answer" to you but throughout this article series you'll read explanations by experts in and out of government and in the References section of each article you'll find more authoritative sources on which these articles are based.

On 2019-11-16 by Colby Roper - are "aluminum only" or COLAR devices safe?

Is it even worth changing the devices out to "aluminum only" devices in an aluminum wired home? Customer is trying to save money, although I know that this is probably not even a good idea! She still wants some kind of pricing on the different repair methods.

On 2019-11-17 by danjoefriedman (mod) - "aluminum only" devices have high failure rate

Sorry but NO. Those devices have an equally high failure rate.


Question: examples of improper aluminum wire connections to switches & aluminum-copper twisted splice

Improper solid conductor aluminum wire connections to a switch and to a splice (C) InspectApedia.com Theo Improper solid conductor aluminum wire connections to a switch and to a splice (C) InspectApedia.com Theo

2019/12/15 Theo said:

I need to ask about aluminum and copper codes I’ll show some pictures below thank you for any information

Legal?

This Q&A were posted originally at ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR

Moderator Reply:

Theo

What is "legal" is in the hands of your local electrical inspector.

However I can see that there is a device marked USE SOLID COPPER or CU CLAD ALUMINUM ONLY.

Yet that device in your photos has solid conductor aluminum wires connected to one of its terminals.

Correctly speaking that violates the manufacturer's device specifications and instructions and therefore should be considered a violation of the National Electrical Code (if you are in the U.S.).

I also see that there is a twisted wire splice mixing copper and aluminum. That connection is unsafe and improper as well.

The ONLY copper-to-aluminum connections recommended by the US CPSC are using the AMP COPALUM or the AlumiConn connector block.

See details at ALUMINUM WIRING REPAIR METHODS

Click to open the ARTICLE INDEX given above to see all or our aluminum wiring articles.


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Continue reading at ALUMINUM WIRING IDENTIFICATION or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see ALUMINUM WIRING HAZARD FAQs - questions & answers posted to this article

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