Is a multiwire branch circuit considered a single circuit for servicing a branch circuit or feeder?

A multiwire branch circuit is indeed considered multiple when servicing a branch circuit or feeder. This classification occurs because a multiwire branch circuit consists of two or more hot conductors that share a common neutral. Each hot conductor can serve different loads and phases, and due to this configuration, it is treated as multiple circuits instead of a single one.

In practical terms, treating it as multiple circuits impacts various aspects of electrical design and safety. It affects load calculations, the proper selection of overcurrent protection devices, and the need for proper disconnection methods. This is essential to prevent issues like overloading the common neutral, which could lead to overheating or even fire hazards.

Understanding this concept is crucial for compliance with the National Electrical Code (NEC) and ensuring that electrical systems are safely and effectively managed.