Due to research conducted by Westmoreland Metallurgical Laboratories, it was found that Copper Clad Aluminum (CCA) and Copper are considered to be similar metals. From a galvanic corrosion standpoint, CCA and copper will not degrade when placed together in a medium. This news might not be new for those veterans of the bimetallic industry, but for those in other industries, such as those working in electrical contracting and municipal inspections, it is truly groundbreaking. Based upon the affirmative data, the NFPA-70 Code Making Panel 1 had sufficient substantiation to amend the National Electrical Code was in Section 110.14 Electrical Connections to allow CCA conductors and Cu conductors to be terminated together in the same circuit. Essentially, CCA and Cu are now considered to be interchangeable from a termination and connector standpoint, and thus can use the same wiring devices, splice connectors and equipment terminals within an electrical circuit.
You can see both the Westmoreland study as well as the Committee statement and new Code language for the 2020 NEC:
