A circuit breaker may be marked with a temperature rating such as 25°C, which specifies what?

The marking of a circuit breaker with a temperature rating such as 25°C indicates the ambient temperature. This temperature rating reflects the maximum environmental temperature in which the circuit breaker is designed to operate safely and effectively.

Understanding this is crucial because circuit breakers are sensitive to temperature variations. The circuit breaker’s performance, including the trip characteristics, can vary with changes in the ambient temperature. At higher temperatures, the trip point may change, which could lead to nuisance tripping or failure to trip under fault conditions.

This temperature rating is important for installations in different environments. For instance, if a circuit breaker is installed in an area where the ambient temperature regularly exceeds the specified rating, the breaker may not function as intended, potentially leading to safety hazards. Therefore, adhering to the specified ambient temperature ensures proper operation and longevity of the circuit breaker.