Which part of the NEC requires an AC substation to have a grounding electrode system?

The requirement for an AC substation to have a grounding electrode system is found in Part III of Article 250 of the National Electrical Code (NEC). This part specifically addresses the grounding and bonding requirements for various types of electrical installations, including substations. The provisions in this section ensure that grounding systems are appropriately designed to safeguard both equipment and personnel by providing a low-resistance path for electrical faults, promoting safety and reliability in electrical installations.

Part III outlines the necessary specifications for grounding electrodes, which are crucial for maintaining the effectiveness of a grounding system. This includes the types of electrodes that can be used, their installation requirements, and the overall performance criteria that must be met to ensure optimal grounding and safety practices in substations and other electrical infrastructure.

Understanding the importance of these requirements helps in comprehending the broader implications of effective grounding in preventing potential hazards associated with electrical faults.