Which statement best describes a CO/ALR marked snap switch's conductor compatibility?

• A. Aluminum conductors
• B. Copper conductors
• C. Copper-clad aluminum conductors
• D. Aluminum, Copper, and Copper-clad Aluminum conductors

Answer: (D)

The main idea here is that CO/ALR marking shows the device is designed to accept multiple conductor materials. A snap switch with CO/ALR is listed for copper conductors and for aluminum conductors, and that compatibility extends to copper-clad aluminum as well, since it behaves like an aluminum-based conductor with a copper surface. This means you can wire the switch using aluminum, copper, or copper-clad aluminum, as long as you follow the installation instructions (such as using anti-oxidant on aluminum conductors and tightening to the specified torque).