Safety advice about using COALR type devices with aluminum electrical wiring: this article explains why COALR, CO/ALR, AL-CU or CU-AL marked devices are not recommended for use with aluminum wiring as a "repair" for aluminum wiring. We explain the differences between COALR, CO/ALR devices and AL-CU or CU-AL devices - they are not equivalent!
Aluminum wire connections can overheat enough to start a fire without ever drawing enough current to trip a circuit breaker. Making proper repairs to aluminum electrical wiring, using the proper electrical wire connectors and methods, can bring the level of electrical wiring safety in building to about the same as a copper-wired building.
Making improper repairs to aluminum wiring might actually increase the level of risk. The history, differences in performance, and significance of COALR, CO/ALR, CU-AL and AL-CU marked electrical devices in aluminum-wired homes. What are the concerns with COALR or CO/ALR -marked electrical devices when used with aluminum wiring.
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Independent tests support the US US CPSC recommendations for repairing aluminum electrical wiring: only the AMP TYCO COPALUM or the King Innovations AlumiConn connector repair - or re-wiring with copper
Electrical Receptacles and switches marked COALR, CO/ALR, AL-CU or CU-AL or CU-Only (photo above right) have not been recommended by the US CPSC for aluminum wiring repairs.
However COALR or CO/ALR - marked devices are not and should not be treated identically with electrical devices marked CU-AL or AL-CU.
Also, devices marked CU-only are intended for use only with copper wire.
Prior to the introduction of the "CO/ALR" wiring devices in about the 1973 timeframe, UL did not have any standard or standard tests for wiring device terminals for aluminum wire. The markings prior to that time regarding type of wire were optional for the manufacturer to apply as they wished. UL considered all wiring devices with screw terminals as suitable for aluminum wire, even if the devices also had push-in backwired terminals.
The photograph shows a back-wired electrical receptacle with an aluminum-wired branch circuit. In the case in these photos the electrical receptacle was marked as "AL-CU" but was further marked as Backwire CU-ONLY by its manufacturer.
["Electrical receptacle" as used in our articles is a synonym for "electrical outlet" or what some people inaccurately call a "wall plug" or "wall socket". "Electrical devices" include receptacles, switches, and possibly other electrical components which are connected to the electrical wiring in a building.
The CU-AL and AL-CU markings were applied by the wiring device manufacturers at their option, without any special testing for compatibility with Aluminum Wire. This was allowed (by UL) until about 1972.
Most of the devices marked this way are identical to those (of the same model # "family" from the same manufacturer) that are not marked AL-CU or CU-AL.
In about 1972, UL and the wiring device manufacturers agreed on a test standard for receptacles for use with Aluminum Wire. The devices that passed the standard were marked CO/ALR.
Five manufacturers initially manufactured "CO/ALR" wiring devices (receptacles and switches), and we believe that one or two continue to manufacture them today.
Since devices marked COALR or CO/ALR conform to the UL standard for compatibility with aluminum wire, the devices with CO/ALR markings must be considered differently - they are not the same as the AL-CU or CU-AL devices.
Wright-Malta Corporation conducted long-term tests of "old technology" (including "CU-AL") wiring devices and CO/ALR devices for CPSC.A total of 1000 receptacles (4000 wire terminations), were tested, including 500 of the CO/ALR (100 of each brand. All of the testing was done within the ratings for the wire size and receptacle application.
[Aronstein reports in summary that there were] "... many failures and burnouts of the "old technology" receptacles, and one failure (burnout) of a CO/ALR device."
Electrical devices that are stamped CU-Only are intended only for use with copper wiring and should not be used with aluminum electrical wiring.
These photographs from a large condominium complex wired with aluminum show aluminum wiring connected to an electrical outlet marked CU-ONLY.
Are switches and receptacles marked with Solid Core Wire Only suitable for use with Aluminum Wire? - D.C.
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem with wiring, use of aluminum wire, and with the connectors, pigtails, or other repairs that have been attempted or that are needed.
That said, the short answer to your question is NO.
Here are some things to consider:
Even CO/ALR devices that the manufacturer has stamped as intended for use with AL wire are not suitable according to industry experts and according to research already performed and documented here. See ALUMINUM WIRING REPAIR NOT-Recommended.
If your building has solid conductor AL wiring the proper repairs are either re-wire with copper or pigtail with copper using a CPSC recommended connector. See ALUMINUM WIRING REPAIR METHODS for details.
Watch out: some "approved" aluminum wire to copper wire connectors that the manufacturer has tested as meeting the appropriate standard in fact do not work, melt, catch fire. And there are no connectors currently sold intended for straight aluminum connections.
Stick with what the CPSC recommends and you'll be ok.
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(Aug 3, 2011) Harold Wehby said:
My apartment building has aluminum wiring,,which outlet should be used to upgrade?
Really? Mr. Wehby as this article explains, no outlet should be used as an "upgrade" to aluminum electrical wiring - as that is not the repair recommended by the U.S. CPSC nor experts in the field. The proper repair is either re-wiring with copper (very costly) or copper pigtailing every single aluminum wire connection in the building - using a connector recommended by the U.S. CPSC such as the AMP TYCO COPALUM connector or the tested AlumiConn from King.
(June 18, 2012) John said:
According to NEC 404.14(C) and NEC 406.3(C)Switches and receptacles rated 20amps or less and designed for direct connection to aluminum conductors shall be marked CO/ALR.
That is so, John, but "designed for direct connection" never addressed the performance of those connectors that have, as described above, not performed acceptably. CO/ALR is absolutely NOT a repair recommended for aluminum wiring, as you'll read in the US CPSC document as well as in research described at InspectApedia
We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Working together and exchanging information makes us better informed than any individual can be working alone.
InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.
(July 9, 2012) Bill Miller said:
I want to respect your institution and its views, but I am finding the aluminum branch wiring issue to be a cross between a witch hunt, jobs program for electrical contractors all rolled into a Chicken Little claim that if you have aluminum branch wiring your house will burn down. Why? According to your own reporting; only 1 in 500 of the COALR didn't perform adequately. You didn't say failed. Also, according to the National Fire Protection Association, for 2005-2010, only 6 percent of house fires were attributed to all forms of electrical malfunctions. Of the 6 percent, 61 percent was attributed to all types of distribution issues. So at best, aluminum branch wiring could be cause for approximately 2 percent of all house fires during this time period. 2 Percent. That is less than candles, smoking, and clothes dryers. 2 percent was the starting level to even make the causal list. What has this unfounded hysteria caused? Well, here in the state of Florida, the insurance companies have jumped on this as a cause to deny coverage. A house with aluminum wiring has only one insurer to use, the state run Citizens, and at nearly double the rate of a copper house. This attack on aluminum wiring has made thousands of Florida homes worthless, as they are unsellable because they can't get insurance. Kitchen fires accounted for 47 percent of house fires, heating equipment 21 percent, intentional 9 percent. So a house with aluminum wiring has a better chance of catching fire if someone uses the kitchen, uses a heater, or if an arsonist attacks it. Aluminum wiring is so far down the list it is not even mentioned specifically as causal. Your results may be factual, but they must be held in context with what the outcome may be. The CPSC also needs to be more up front in how it presents data and suggestions. It is outrageous to claim aluminum wiring and COALR devises are unsafe when the total picture is viewed in a cause/effect based outcome.
(Aug 18, 2014) Jay said:
I would like to know who wrote this article. I totally agree with Bill about the scare mongering in Florida. If aluminum wiring is as dangerous as this article implies explain to me why hundreds of thousands of homes with it are still standing in the all over the US. Thank you Bill for putting the "danger" in perspective.
Bill, thank you for the courteous disagreement. Unfortunately the hazardsfrom aluminum solid conductor branch wiring are very real, not theoretical, and have been amply studied and reported as we document in articles at this website. In addition we continue to receive field reports of fires, overheats, burnups, etc/
The COALR concerns are documented above and represent the experience, tests, and views of sources we judge to be unbiased professionals with no skin in the issue.
When we read comments asserting that the aluminum wiring hazard is unreal I often find that the source is one who has a financial stake in the matter. Or who is uninformed.
I share your objection to hysterical reporting and I assure you that we are scrupulous in editing and rejecting such reporting as it serves no one and risks consumers being ripped-off by aggressive folks who may be selling snake oil or worse. So I am doubtful that you will find hysteria in the reporting at InspectApedia but if you do find errors of fact or omission or presentation I'd welcome hearing specifics.
The position of the insurance companies on aluminum wiring derives principally from their loss data, not from a wish to burden homeowners with needless expense.
InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.
We are absolutely dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Contributors, even if it's just a small correction, are cited, quoted, and linked-to from the appropriate additional web pages and articles - which benefits us both. Working together and exchanging information makes us better informed than any individual can be working alone.
I want to add that in my own meetings with engineers and management from the US CPSC I was very impressed with the technical depth of the engineering department and the great caution with which the agency considered advice to consumers. I did not see any evidence of superficiality, scare mongering, nor conflicts of interest in the public information about aluminum wiring hazards. I have on occasion found conflicting interests among a very few folks from several industries who put profit before safety.
Finally, while the repair option of re-wiring is very costly and rarely followed except in renovations, the other options for pigtailing are plausible and to me and to experts in the field, make perfect sense. In my experience it has been very rarely the case that someone undertook a proper aluminum wiring repair without discovering burned, overheated connections in their home.
The information provided in the InspectApedia series of articles on aluminum wiring safety is based on professional citations dating from the 1970's to the near present. These can be seen in the References section of most of the pages on this topic.
Unfortunately for your point of view, and with all due respect, the research and the field experience with fires, even fatalities, associated with aluminum solid conductor branch wiring are amply documented with decades of research, experience, testimony, and expert advice.
(Oct 2, 2012) Thomas M. said:
I recently rewired my 1927 house. It appears to have been 'upgraded' at sometime with BX armored Al cable (ungrounded) sometime in the past. All the BX that I could get to was pulled or decommissioned if I couldn't actually pull it out (I usually rerouted the new Cu 12/2 cable from another direction). Right now I have old BX connected to four light switches for ceiling or outdoor lights--getting the cable out and replacing/rerouting is a huge & damaging task and is why they are still there. After reading up here, I am somewhat discouraged about what to do. Also, I erroneously pulled the old light switches (unmarked or Cu Al types) and replaced them with Cu only. That is a near future project to correct. None of these had charring or scorches on them, but the insulation is dried out & needed taping.
However, two questions
I want to swap out the Cu switches with CO/ALR switches (I avoid backwiring), the main reason are the boxes are shallow and crowding with pigtails in other boxes was incredibly difficult with receptacle boxes, and it appears that the alumiconn method could be problematic space-wise. it would be connected to Al only and no receptacles are on the same circuits. Not sure what to do or believe--the main consensus I read is that the Al wiring itself is not the problem, but improper connections & splicing, particularly with Cu wiring and Cu only devices.
Second is that if swapped out, I don't consider this a 'complete' repair because the far greater issue I see are where the switch cables go: to junction boxes with all new Cu cable where those have to be respliced with proper connectors. This sight was very clear about what is advocated as proper and all the alternate known methods deemed improper. Which is the greater problem?
If CO/ALR is considered not a true repair, then why do manufacturers still make and sell it? This seems like a liability risk.
Thanks for this excellent resource.
9/26/14 Anonymous said:
This article is a problem. My house has aluminum wiring and recently I have experienced some arcing in the receptacles. The connections to the plug were very loose and there was difficulty sometimes in making a good connection. I have replaced a portion of the receptacles with Cooper Devices CO/ALR dual receptacles. The difference is very noticeable. This is a quick fix anyone can do. You seem to be discouraging people from reducing the risk with a fix that is approved. The receptacles that I removed were not marked with the CO/ALR and after 40 years of use are still functioning. This whole article is misleading and I would say dangerous.
With all due respect, the problem is not this article unless we failed to make clear the following: CO/ALR dual receptacles that you tout are *NOT* recommended by the US CPSC for aluminum wiring repairs. The U.S. CPSC is the key authority in this matter - folks who have taken pains to specify which aluminum wiring repairs work and are safe when properly executed. The "repair" you like is not one of them.
Your second observation, that the old receptacles you removed "are still functioning" needs to be undertood in the context of how overheating occurs at connections and how that leads to fires. "Functioning" in the sense of passing along electricity through a duplex receptacle to the device plugged-in does not mean "safe". A small change such as wiggling around a receptacle or switch by plugging devices in and out of it or by flipping a switch on and off add movement that can be a source of loose connections.
But even without *any* such movement, as Aronstein's research points out, a combination of oxidation and micro-fretting at the connection points of aluminum to copper receptacle or switch screws leads to a cycle of increased heat, increased oxidation and corrosion, until an overheat and possibly a fire occurs.
On homes where all of the devices have been removed and replaced as part of aluminum wiring repair, it is certainly the case that not every device shows signs of overheating. But after several decades of independent research and receipt of field reports on aluminum wiring overheats and fires, we see that during an aluminum wire repair at a building, it is very very rare for the electrician to fail to find at least one dangerously overheated device, connector or receptacle or switch.
Happily not all overheats burn the building down. Many are contained within the junction box and some simply burn enough to shut off the circuit.
OPINION: One can but wonder if some of the gripes about the US CPSC's position on non-recommending the use of COALR and CO/ALR or CU/AL-marked devices as an aluminum wiring "repair" originate with folks who have a financial interest in selling those devices. If that sould be the case, one might be more confident in the US CPSC and in the work by independent researchers who have no skin in the sale of particular products.
You should rely on COALR or CO/ALR devices if you want to follow the advice of those independent experts who have no conflicting interests.
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