Snap switches connected to aluminum conductors must be marked CO/ALR if they are rated at what maximum amperage?

Snap switches connected to aluminum conductors need to be marked CO/ALR when they are rated for a maximum amperage of 20 amperes. This marking indicates that the switch can safely be used with aluminum conductors, which require specific considerations due to the properties of aluminum compared to copper.

Aluminum conductors have a tendency to expand and contract with temperature changes, which can create a risk of loose connections over time. The CO/ALR marking signifies that the switch has been designed and tested to ensure safe operation with aluminum wire, thereby preventing potential overheating or failure at the rated current levels. Therefore, for switches rated at 20 amperes, the CO/ALR mark is critical to ensure compliance with safety standards and regulations.

Other amperage ratings mentioned do not require this specific marking. For instance, while switches rated at 15 amperes may also be used with aluminum conductors, they are not mandated to have the CO/ALR designation. Hence, the focus on 20 amperes specifically aligns with the need for additional safety measures when using aluminum conductors.