time instead of 235A? No, the 1.5-9 seconds is not slow enough that the wire will already melt before it trips the circuit breaker.

While it is true that the #12AWG wire has a fusing current of 184A at 30 seconds in your lab conditions, you have to consider the fact that these calculations are theoretical and may not reflect real-world scenarios accurately. Real-world factors such as wire condition, insulation material, circuit breaker responsiveness, and other environmental factors can impact actual outcomes. With a 40A "D" curve circuit breaker, it is designed to trip between 1.5-9 seconds when 184A of current is flowing through it. However, there is a possibility that the circuit breaker may not trip in time or within the intended range, which may expose the wire to a longer period of high current flow. Although it is estimated that the wire will melt in 30 seconds with a current of 184A, exposing the wire to a high current close to its fusing value for 1.5-9 seconds could still lead to degradation, increase in temperature, and damage to the wire. In short, although the circuit breaker should theoretically trip between 1.5-9 seconds preventing the wire from reaching its 30-second melting point, you may still risk damaging the wire and increasing the risk of an electrical hazard due to the real-world complexities and potential deviations from calculated values. To ensure safety and minimize the risk of damage, it is recommended to use a circuit breaker with a lower trip time, or to use wire with a higher current rating that matches the protective devices incorporated into your experiment.