It is my understanding that outlets can have wires connected on both sides. Example from another DIY.SE question here . If I have aluminum wiring. I want to add another downstream outlet. I will use an appropriate CO/ALR outlet. I will verify that the circuit can handle the additional load.

Can I have aluminum wiring on one side of a socket and copper on the other?

I am specifically asking if this AL to CU junction can be handled by the two sides of an outlet as opposed to an AlumiConn or Tyco connector.

  • There is also CU-AL wire (aluminum core with copper shell) which - as far as I know - does not have the same requirements (e.g., can be treated more like normal copper). I assume that this is not what you have. Jul 23, 2016 at 2:56
  • @DaveInCaz - I wish I had CU-AL! I have regular AL wiring and I have the early form of it. In later years different alloys were used which reduce the risks.
    – Freiheit
    Jul 25, 2016 at 15:41
  • CO/ALR receptacles and devices are not recommended by the CPSC and independent researchers as a proper Aluminum wiring "repair".
    – TrinitronX
    Dec 6, 2019 at 20:02
  • Dr. Aronstein, states: "Some CO/ALR wiring devices that are available are old stock and should not be used. The indium plating used on the screw terminals of some brands degrades with time, so the devices have a limited shelf life. Inspect the screw terminals and the terminal plate. If the terminals have a fresh metal look, they are probably OK. If the screws and/or terminal plate look tarnished or off-color, do not use them with aluminum wire, as the long-term performance and safety would be questionable." However, the CPSC does not recommend any CO/ALR devices. Only COPALUM or Alumiconn
    – TrinitronX
    Dec 6, 2019 at 22:37

1 Answer 1


The manufacturer of the receptacle should make this detail clear in their documentation. It might even be printed on the case of the receptacle, though perhaps in very abbreviated / "hieroglyphic" form.

That said...

My understanding is that aluminum wiring must be used ONLY with approved mechanical connectors specifically designed for aluminum, and of course must be installed correctly. So I do not see, offhand, why a separate copper connection on the same device would be a problem.

[Note - I am not an electrician. Aluminum wire done incorrectly is a huge fire hazard, which the OP obviously knows since s/he is obviously intending to do this right.]

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