What voltage rating defines Class 2 wiring typically used for doorbells and thermostats?

Class 2 wiring is defined by the National Electrical Code (NEC) for low-voltage applications such as doorbells, thermostats, and other similar devices. The key voltage rating that characterizes Class 2 circuits is a maximum of 60 volts for these applications, although the NEC allows for certain modifications that permit even higher ratings in specific situations.

Among the provided choices, 150 volts is significant because it represents a threshold often associated with Class 2 circuits, which can include allowances for systems connected to loads that can tolerate slightly higher voltages under specific conditions. It is crucial to note that while Class 2 wiring is predominantly utilized in lower voltage applications, the classification incorporates aspects of safety and voltage limits designed to minimize risks related to electrical shock or fire hazards.

In this context, choosing a voltage rating at or just above the nominal threshold of low voltage systems, such as 150 volts, aligns with the NEC's guidelines about Class 2 wiring, making it the correct answer for this question. The other voltage options either exceed typical Class 2 limits or do not correspond to this classification's accepted standards.