Equipment for General Use
Articles 400 through 490
This chapter governs the equipment you install every day. Flexible cords and cables (400) may not be used as permanent wiring or as a substitute for fixed wiring. Switches (404) must be readily accessible and, per 404.4, may not be installed within reach of a bathtub or shower. Receptacles (406) must be grounding type, tamper-resistant where required in dwellings, and weather-resistant with an appropriate cover in damp and wet locations. Luminaires (410) have restrictions in clothes closets and near combustible material. Appliances (422) require a disconnecting means and sizing per nameplate. Fixed electric space heating (424) is a continuous load at 125%. Transformers (450) use Table 450.3 for overcurrent protection. Article 625 covers EV charging, and 605/645 cover office furnishings and IT equipment.
Traps
Treating cord-and-plug connection as a legal permanent wiring method, forgetting the 125% continuous multiplier for heaters and water heaters, misapplying Table 450.3 transformer protection percentages, and ignoring the specific restrictions on luminaires in closets or receptacles near sinks.
Worked example
A 5,500 W, 240 V fixed wall heater: 5,500 ÷ 240 = 22.9 A. As a continuous load, 22.9 × 1.25 = 28.7 A, so use 10 AWG copper conductors and a 30 A overcurrent device with a disconnect in sight of the unit.