Equipment, Devices, and Utilization Equipment
Equipment, devices, and utilization equipment
This domain covers how equipment is selected, rated, connected, and protected. Key articles include 404 (switches), 406 (receptacles), 408 (panelboards), 410 (luminaires), 422 (appliances), 424 (fixed electric heating), 430 (motors), 440 (air conditioning and refrigeration), and 450 (transformers). Equipment must be listed and installed per its listing and nameplate. Receptacle ratings must be coordinated with branch-circuit ratings and permissible loads. Switches and disconnects must be accessible and rated for the load, and motor circuits require separate branch-circuit short-circuit/ground-fault protection and overload protection.
Traps and a worked example
Traps include putting a 15 A single receptacle on a 20 A individual branch circuit (not permitted; a single receptacle must have a rating not less than the branch circuit), confusing GFCI and AFCI functions, using a breaker for motor overload protection instead of a separate overload device, and ignoring nameplate minimum circuit ampacity and maximum overcurrent protection on A/C equipment. Another trap is assuming a disconnect can be anywhere; many rules require it within sight of the equipment.
Worked example: a 10 hp, 460 V, three-phase motor has a nameplate full-load current of 14 A. For a standard inverse-time circuit breaker, 430.52 permits up to 250% of FLC: 14 A × 2.50 = 35 A. A 35 A breaker is a standard size, so it is acceptable as branch-circuit short-circuit/ground-fault protection, provided the separate overload protection is sized per the motor nameplate or 430.32. Rule of thumb: motor branch protection protects the circuit, not the motor; overload protection protects the motor.