Tuesday, January 17, 2023
We have probably all read the term copper clad aluminum in the NEC but many of us have never seen this conductor. It was used for a while after we stopped using aluminum for small branch circuits but dropped off when cooper prices fell. It has seen a recent resurgence and several code changes for the 2023 NEC are based on the use of Copper Clad Aluminum (CCA). This type of conductor has been in the National Electrical Code since 1971 and is now making a comeback.
CCA is a bimetal product created by an industrial process called cladding. A bimetal is a metal that has two distinct metallic zones united by a metallurgical bond that is stronger than the two materials it unites. The core is made from AA 8000 series aluminum, and the exterior layer is high-purity (99.8% O2-free) copper. The low oxygen content minimizes conductor oxidation, which means antioxidant joint compounds are not required at terminations. The cladding process results in a unique metal, stronger than the two metals it unites, and creates a conductor that is pliable, elastic, thermally stable and strong.
A little history
Due to copper shortages in the early 1950s, cable manufacturers came up with a conductor made from electrical-grade 1350 aluminum. By the 1960s, aluminum building wire was widely installed all over the country. However, by 1968, the aluminum building wire used for branch circuits was identified as a hazard because it was subject to thermal instability and galvanic corrosion when terminated to the wiring devices of the era. These problems were responsible for a product recall unequaled in the electrical industry at the time.
Soon after 1350 aluminum conductors were pulled from the market, CCA emerged as a solution. It was brought to Underwriters Laboratories for performance testing in the late 1960s, and it was allowed into the 1971 NEC, making it one of only three conductors permitted by the Code.
CCA was widely used for the next decade because the price of copper remained high. Its use greatly decreased after the end of the Vietnam War when copper prices plummeted due to diminishing demand by the military. CCA, with its high material and manufacturing costs, could no longer compete with commodity-copper conductors. Copper prices remained very low for many years until around 2005, creating an opportunity for CCA to re-emerge as an alternative.
CCA versus aluminum
CCA has several advantages when compared to aluminum conductors:
Terminations—CCA, with its copper cladding, can be terminated to copper-only termination and splice points, which are often less expensive than CU/AL terminations.
Strength—Due to its manufacturing process, CCA has superior tensile strength and pliability compared to aluminum-only conductors.
Voltage drops—Due to CCA’s copper cladding, it has less voltage drop compared to aluminum.
CCA versus copper
CCA also has advantages when compared to copper-only conductors:
Voltage drops—It may be hard to believe CCA has superior voltage drop characteristics compared to copper. However, when up-sizing for ampacity as required by the NEC, CCA provides approximately 8% more current-carrying capacity when compared to the same rated copper.
Theft—As copper prices rise, so does theft. The copper in CCA is very hard to remove. In terms of scrap value, the two base metals contaminate each other, making it very unattractive for scrap dealers.
Weight—CCA is significantly lighter than copper, making it easier to handle and install. Labor-saving alternatives are welcomed by estimators looking to be competitive.
Terminations—CCA can be terminated on copper-only termination points, which can save money on CU/AL terminations, splices and adapters.
Price—At the time of this writing, CCA costs about 10% less than copper. This changes daily as the price of copper fluctuates.
Availability
CCA is available in most commonly used insulations, including THHN, THWN, XHHW and USE. Currently, it is popular for NM and MC applications for residential and commercial projects and is available as service cable in Types SER and SEU. CCA has also become popular for several low-voltage applications, including coaxial and twisted-pair cables. It is not available for Cat-rated cable due to signal performance issues.
CCA has been in the NEC since 1971 in sizes No. 12 and larger. Regarding ampacity, it is listed to be the same as aluminum. Size No. 14 is being considered in the current Code cycle with a rating of 10A. This could be very useful for the many low-amperage circuits we are seeing for LED lighting applications.
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