No. 18-2 or 20-2 insulated wire may be used for connections between which of the following?

The use of No. 18-2 or 20-2 insulated wire is commonly associated with low-voltage applications, such as those utilized in signaling or control circuits. This makes the connection between chimes and pushbuttons an appropriate use for such wire gauge. These components often operate within low voltage ranges, and using smaller gauge wire like No. 18-2 or 20-2 is sufficient for the current requirements, ensuring both safety and functionality.

In contrast, while transformers and light bulbs, as well as switches and outlets, might also involve connections in electrical systems, they typically handle higher voltage and current capacities that may require larger gauge wires to ensure safety and adequate power delivery. Using the smaller gauge wire for these higher capacity applications could lead to potential safety issues, such as overheating or voltage drop. Thus, the connection between chimes and pushbuttons remains the most suitable application for No. 18-2 or 20-2 insulated wire.