Amp Up Your Skills with the 2026 Electrician's Licensing Exam – Spark Your Path to Success!

In the context of National Electrical Code (NEC) regulations, Section 250.66 specifically addresses the size of grounding conductors for both grounded and ungrounded systems. This section provides the necessary tables and calculations to determine the appropriate conductor size based on the rating or setting of the overcurrent device. Proper sizing of grounding conductors is crucial for ensuring safety and effective fault current dissipation.

The other sections mentioned include topics that are not primarily focused on grounding conductor sizes. For instance, while Section 250.122 deals with the sizing of equipment grounding conductors based on the rating of the overcurrent protection, it is not the main reference for grounding conductor sizes themselves. Section 250.2D pertains to grounding methods and their applications, and Section 225.18 focuses on additional grounding requirements for outside branch circuits or feeders. Thus, Section 250.66 remains the correct and appropriate reference for grounding conductor sizes.