LGE-3 — General-Use Equipment

Exam checkpoints

Classify before you calculate

General-use equipment is a code-navigation cluster, not one calculation rule. Start with the article that describes the equipment: Article 400 for flexible cords, 404 for switches, 406 for receptacles, 422 for appliances, 424 for fixed electric space heating, 430 for motors, 440 for air-conditioning and refrigeration equipment, 445 for generators, and 450 for transformers. Then apply Chapters 1 through 3 for listing, working space, conductor ampacity, overcurrent protection, wiring methods, boxes, grounding, and environmental conditions.

Read the nameplate and listing before selecting conductors. Voltage, phase, frequency, ampere or horsepower rating, minimum circuit ampacity (MCA), maximum overcurrent protection (MOCP), duty, temperature, and short-circuit ratings answer different questions. A nameplate does not replace the NEC, and a familiar-looking device does not authorize an installer to ignore its instructions.

Switches, receptacles, and cords

Article 404 generally places switches in ungrounded conductors so opening the switch de-energizes the controlled load. A switch in the grounded conductor alone can leave equipment energized. Section 404.2(C) requires a grounded circuit conductor at many lighting-control switch locations, subject to its raceway, accessibility, and other stated exceptions; do not call this conductor an equipment ground. Metal faceplates and switches are grounded and bonded under 404.9, and switches in wet or damp locations need an enclosure suitable for the environment.

Match the switch to the load. A general-use snap switch has ampere, voltage, and load-type limits. A motor load may require a horsepower-rated controller or a listed motor-circuit device. A thermostat or pushbutton can command equipment off while line terminals remain energized, so the applicable equipment article still decides whether and where a disconnect is required.

Article 406 coordinates receptacle configuration, rating, grounding, replacement, tamper resistance, and weather protection. On a 20 A branch circuit supplying two or more receptacles or outlets, a 15 A receptacle is permitted by Table 210.21(B)(3); a lone single receptacle on an individual 20 A circuit must have a rating not less than the circuit. Do not install a 15 or 20 A receptacle on a 30 A general branch circuit.

When replacing a nongrounding receptacle where no equipment grounding conductor exists, 406.4(D) permits specified options, including a GFCI-type replacement marked No Equipment Ground, or a grounding-type receptacle supplied through GFCI protection and marked GFCI Protected and No Equipment Ground. GFCI protection reduces shock risk but does not create a grounding conductor for surge equipment or metal bonding. Apply required AFCI, tamper-resistant, and weather-resistant replacement provisions separately. Wet-location receptacles need the applicable weatherproof enclosure while a plug is inserted.

Flexible cord is allowed only for uses in 400.7 and is prohibited as a substitute for fixed wiring under 400.8. Do not conceal it in walls or ceilings, run it through holes in walls, structural ceilings, suspended ceilings, floors, doorways, or windows, or attach it to building surfaces unless a specific permission applies. A cord-and-plug connection can serve as a disconnect only where the equipment article and listing allow it and the plug remains accessible.

Appliances and fixed electric heat

Article 422 appliances are listed under 422.6 and installed from their nameplate and instructions. Size branch circuits under 422.10 and the applicable load rule; household cooking appliances, water heaters, disposals, dishwashers, and commercial appliances do not all use the same demand or cord permission. Section 422.16 permits flexible cord only for listed appliance arrangements and conditions, not as a general alternative to a required outlet and fixed wiring.

Sections 422.30 through 422.34 govern appliance disconnects. A unit switch may serve only when it meets the required off-position and disconnection conditions; otherwise use an accessible attachment plug or a disconnect within sight or capable of being locked open as the applicable rule permits. A fixed storage-type water heater of 120 gal or less is considered a continuous load under 422.13. Its branch-circuit conductors and rating are therefore at least 125 percent of the nameplate: a 24 A water heater requires at least 24 × 1.25 = 30 A before applying terminal, conductor, and protection rules.

Fixed electric space-heating loads under Article 424 are also generally sized as continuous loads. Conductors and overcurrent protection are ordinarily at least 125 percent of the total heating load, and the heating equipment requires the disconnect and controls specified by the article. A thermostat is a disconnect only when it has a marked off position, directly opens all ungrounded conductors, and meets the applicable rating and lockout conditions.

Keep the three motor protections separate

Article 430 separates branch-circuit conductors, running-overload protection, and branch-circuit short-circuit and ground-fault protection. For a single continuous-duty motor, 430.22 generally sizes conductors at 125 percent of the full-load current selected under 430.6(A)(1), commonly from Tables 430.247 through 430.250 rather than the motor nameplate. If the applicable table current is 32 A, minimum conductor ampacity is 32 × 1.25 = 40 A before adjustment, correction, and terminal limitations.

Overload protection under 430.32 ordinarily uses motor nameplate current. Motors marked with a service factor of at least 1.15 or a temperature rise of 40°C or less can generally use 125 percent; other motors generally use 115 percent. Branch-circuit short-circuit and ground-fault protection follows 430.52 and its table. Its permitted fuse or breaker can be larger than conductor ampacity to allow starting, because overload protection provides the running-overload function. Do not apply the next-standard-size rule or increase protection without checking the exact motor provision.

A controller starts and stops a motor; a disconnect isolates it. Check horsepower, voltage, and current ratings and the 430.102 location rules. A stop button or VFD command is not a disconnect. The required disconnect is in sight where mandated or uses the limited lockable-open alternative allowed by the article and installation conditions.

Let packaged HVAC markings do their job

Article 440 applies to hermetic refrigerant motor-compressors and covered HVAC/refrigeration equipment. For an individual compressor, conductor sizing uses the rated-load current or branch-circuit selection current, whichever is greater, at the Article 440 multiplier. For a listed condensing unit or packaged system marked MCA and MOCP, choose field conductors with ampacity at least the marked MCA after applicable corrections, and do not exceed the marked MOCP. An MCA of 28 A with MOCP of 45 A is not automatically a defect: conductor sizing, starting-current protection, and internal overload protection perform different functions.

Section 440.14 requires the equipment disconnect to be readily accessible and within sight of the HVAC or refrigeration equipment, with its stated exceptions, and it cannot be mounted on a panel designed to provide equipment access. The disconnect, raceway, fittings, conductors, and enclosure must suit outdoor wet-location and temperature conditions. A maintenance receptacle is a separate outlet and should remain usable when the equipment disconnect is open.

Transformers and generators complete the map

Article 450 governs transformer overcurrent protection, installation, ventilation, guarding, and separation from combustible material. Apply Table 450.3 to the transformer, then separately protect or size secondary conductors under 240.21(C). Primary protection does not automatically protect every secondary conductor. If a transformer secondary is a separately derived system, establish its system bonding jumper, grounding electrode conductor, and equipment grounding paths under 250.30; not every transformer connection is separately derived.

Article 445 covers generator nameplates, conductors, protection, and disconnecting means, while the system supplied may also invoke Articles 700, 701, or 702. A generator neutral is not automatically separately derived. The transfer equipment determines whether the grounded conductor remains solidly connected to the normal source or is switched, which in turn changes bonding and grounding treatment. Finish every equipment question by checking the listing, disconnect, grounding, environment, working space, and all source-specific overcurrent rules.