What is the minimum size of the equipment grounding conductor between the panel and the pull box?

The minimum size of the equipment grounding conductor (EGC) plays a crucial role in ensuring safety by providing a low-resistance path for fault currents, preventing electrical shock and equipment damage. According to the National Electrical Code (NEC), the size of the grounding conductor is determined based on the rating of the overcurrent protection device and the material of the grounding conductor being used (copper or aluminum).

When it comes to sizing the grounding conductor, it is essential to reference NEC Table 250.122, which outlines the minimum size requirements based on the rating of the overcurrent protection in the circuit. The proper sizing ensures that the grounding conductor can handle fault currents effectively without being damaged.

The choice of 3 AWG as the minimum size is derived from specific conditions outlined by the NEC regulations that apply in situations where there are certain lengths and configurations, ensuring that even under fault conditions, the EGC can perform its intended function without risking failure.

In summary, 3 AWG is the correct answer because it satisfies the NEC requirements for the necessary current-carrying capacity and safety for equipment grounding conductors in this context.