Which article provides guidance on branch-circuit calculations for determining the size of a service or feeder?

Article 220 of the National Electrical Code (NEC) focuses specifically on branch circuit, feeder, and service calculations. It provides the necessary guidelines for determining the appropriate size of conductors and overcurrent protection devices based on the load requirements and the type of installation.

This article outlines the different approaches to calculate the load, taking into account factors such as continuous loads, demand factors, and any applicable correction factors that may affect the total demand on service equipment. Understanding this article is crucial for ensuring that electrical systems are properly sized for safety and efficiency, preventing issues related to overloads or underutilization of electrical circuits.

The other articles mentioned, while important in their own rights, address different aspects of the NEC. For example, Article 210 primarily deals with branch circuits and their requirements but does not focus on calculations for sizing services or feeders. Articles 240 and 250 cover overcurrent protection and grounding, respectively, but they do not provide the comprehensive load calculations that Article 220 does.