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Chapter 2 contains the requirements for wiring and protection. But how can you find the requirements that pertain to what you’re working on without missing something important?
The key lies in understanding how Chapter 2 is organized, and why it’s organized that particular way. There’s logic to the sequence.
In our previous issue, we looked at the requirements for grounded conductors in Article 200. Then begins a sequence: branch circuits, feeders, calculations (for branch circuits, feeders, and services); outside branch circuits, feeders, and services. See the pattern? You’re starting from the load and going toward the source. These articles are in a sequence that matches the electrical design process for a building.
But the next four chapters don’t follow this sequence. Why? Obviously, overcurrent protection (240) applies to branch circuits, feeders, and services. Rather than have a separate article for each level of circuit, there’s just this one. The same is almost true for Article 250, which provides the requirements for grounding and bonding. It’s almost true, because we bond, not ground, feeders and branch circuits.
Surge protective devices (280) could also apply to all levels of circuits. Surge arrestors (285), while typically installed ahead of the service, can also be used anywhere in the system, if the voltage level is high enough. Fermi (Batavia, IL), for example, has surge arrestors installed on high voltage detector circuits.
Though Chapter 2 is long, it need not be confusing or overwhelming.
Source: Mark Lamendola | Mindconnection