For motors rated at over 10 HP, which standard must be referred to for necessary protection?

When dealing with motors rated over 10 HP, it's essential to refer to Article 430 of the National Electrical Code (NEC). This article specifically covers the requirements for motors, including installation, overcurrent protection, branch circuit conductors, and other aspects crucial for ensuring safe and efficient operation.

Article 430 is designed to address the unique challenges that arise with larger motors, such as the higher current levels and potential for increased heating. It provides guidance on the necessary sizing of conductors, overload protection devices, and the coordination between protective elements to prevent motor damage and ensure reliable operation.

The other articles listed serve different purposes: Article 220 focuses on branch circuits and load calculations, Article 250 relates to grounding and bonding, and Article 300 deals with general requirements for wiring methods and materials. While all these articles are important in their respective areas, they do not specifically address the protection and requirements for larger motors as comprehensively as Article 430 does. Thus, for a motor rated over 10 HP, Article 430 is the essential standard to ensure proper protection and compliance with safety codes.