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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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Use of COALR, CO/ALR, AL-CU or CU-AL or CU-Only Marked Electrical Devices, Switches or Receptacles with Aluminum Wiring
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 marked CU-Only
Electrical devices that are stamped CU-Only are intended only for use with copper wiring and should not be used with aluminum electrical wiring.
Should COALR or CO/ALR or CU-AL or AL-CU -Marked Devices Be Used With or as a "Repair" for Aluminum Wiring?
These photographs from a large condominium complex wired with aluminum show aluminum wiring connected to an electrical outlet marked CU-ONLY.
Reader Questions & Comments on Aluminum wire and CO/ALR CU-AL Devices
Question: What switches or receptacles are OK to use with Solid Conductor Aluminum Electrical Wiring?
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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