Trickling into the US market by 1971, CCA was seen as the most promising material for use in residential BCBW.
First and foremost, it was safe and affordable. Even though it was slightly more expensive than the cheaper EC grade aluminum building wire, which was on the way out anyway, Copper Clad Aluminum Wire still offered considerable savings over expensive solid copper.
Second, it was nearly three times lighter than copper diameter per diameter, making hand-toting heavy coils less of a chore, and pulling wire at the job-site a breeze. It was flexible, but yet sufficiently strong to pull through studs.
Third, it was not brittle like solid EC grade aluminum building wire that caused the fires during the 1960s, and peeling the insulation to make connections was no different than with copper wire.
Finally, because of the thick copper cladding covering the surface of the bare conductor, there was no fear of galvanic corrosion nor creep over decades of use in the circuit. The same copper connectors and devices could be used regardless if a contractor installed solid copper or CCA.