For most systems, selective coordination is a design consideration but not mandatory; for some systems and circuits, selective coordination of the OCPDs is mandatory per the NEC.

For most systems, selective coordination is a design consideration but not mandatory; for some systems and circuits, selective coordination of the OCPDs is mandatory per the NEC.

• A. Design consideration, not mandatory
• B. Mandatory by NEC
• C. Not a concern
• D. Only for residential systems

Answer: (A)

Selective coordination is about making sure that, when a fault occurs, only the nearest protective device trips, so the rest of the system keeps power and the outage is limited. For most systems, engineers treat this as a design choice: you weigh the benefits of tighter coordination against costs, device availability, and the potential for nuisance tripping, aiming for an effective balance rather than a blanket requirement. The NEC does impose requirements in certain contexts—such as life-safety or critical-load systems—where coordination must be demonstrated, but these aren’t universal across all installations. Because of that, the general rule is that selective coordination is a design consideration rather than an across-the-board NEC mandate. In some projects, you’ll encounter mandatory coordination requirements, while in many residential or small commercial setups it’s not forced by code, though it may still be pursued as best practice.

Selective coordination is about making sure that, when a fault occurs, only the nearest protective device trips, so the rest of the system keeps power and the outage is limited. For most systems, engineers treat this as a design choice: you weigh the benefits of tighter coordination against costs, device availability, and the potential for nuisance tripping, aiming for an effective balance rather than a blanket requirement. The NEC does impose requirements in certain contexts—such as life-safety or critical-load systems—where coordination must be demonstrated, but these aren’t universal across all installations. Because of that, the general rule is that selective coordination is a design consideration rather than an across-the-board NEC mandate. In some projects, you’ll encounter mandatory coordination requirements, while in many residential or small commercial setups it’s not forced by code, though it may still be pursued as best practice.