How to Recognize Aluminum Electrical Wiring in Buildings

Find Here:  Tips and photographs helpful in identifying the presence of aluminum wiring in residential/commercial properties. Because we've had requests for help in identifying this wire we've included some tips. Be sure to also look at other photographs available at the Aluminum Wiring Website as many of them show close-ups of aluminum wire in various applications.

Click on the thumbnail sketches below to see each full-sized illustration.
WARNING: do not open or disassemble or touch any electrical panels, devices, components if you are not trained and competent. There is risk of fatal electric shock.

• When was the house built or re-wired or when were circuits added? buildings built, rooms added, circuits rewired or added between 1965 and 1973 may contain aluminum wiring.
• Don't assume that there's no aluminum wire if your house was not built during these years. Circuits may have been added, extended, modified using aluminum wiring. Or an installer may have had leftover aluminum wire and used it after these dates.
• Look at wire at circuit breakers in the electric panel for aluminum wire. The pen in the circled area points to bare silver-colored wire visible at the circuit breaker. Notice that the aluminum wire in this photo is a single circuit installed between two copper wires (on adjacent breakers). Also Look at bare wire exposed at the neutral bus. An easy place to look for aluminum wire than at the circuit breakers might be at the neutral bus where both white neutral wires and ground wires are connected in a row. There it's easier to see exposed portions of the wire itself.
  
  
  
  
   
• Look for the word "Aluminum." Look at for printed or embossed letters on the plastic wire jacket where wiring is visible in the attic or at the electric panel. Some aluminum wire has the word "Aluminum" or a specific brand name such as "Kaiser Aluminum" plainly marked on the plastic wire jacket. This photo shows a dark colored wire jacket with green print indicating "Kaiser Aluminum." Some white colored plastic wire jackets are inked in red; others have embossed letters without ink and are hard to read. Try shining a light along the wire.
  
  
  
  
  
  
  
   
• Don't assume there's no aluminum wire just because you find none in the panel. Aluminum may have been used for part of circuits or for some but not other circuits in the building.
• At outlets and switches, look at stripped wire ends. Often simply removing the cover plate will give sufficient view. Be especially cautious if you see back-wired receptacles. It may be difficult to see if the wire is aluminum, but if it is, the smaller wire contact surface when this method was used may increase the risk of overheating or other failures.
• In the attic look at the wire gauge or "size." Look for #12-gauge wires in the attic or other places where wiring is readily available. If you see only #12 and no #14, look further. Aluminum wire must be one wire gauge size larger for a given circuit than if copper was used. So while #14 copper wire is permitted on a 15-amp electrical circuit, if aluminum wire was used for the same circuit it would have to be #12. Similarly, a 20-amp circuit uses #12 copper wire or #10 aluminum wire. Common residential lighting and electrical-receptacle circuits are 15-amp or possibly 20-amp (e.g. in a kitchen). So if you see only #12 or larger wires in the attic of your house look further to see if it's aluminum. The wire-gauge size is printed or embossed on the wire jacket. #12 does not guarantee it's aluminum, it's just more data to point in that direction.

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