NEC Architecture cheat sheet

Article 100 definitions: 'Approved' means acceptable to the AHJ; 'Listed' means equipment evaluated by a NRTL and included in a published list.

90.4: The AHJ has final interpretation and may grant exceptions; enforcement is the AHJ's responsibility.

110.3(B): Equipment must be installed and used in accordance with its listing and labeling instructions.

110.12: Work must be performed in a neat and workmanlike manner; unused openings must be closed.

110.26(A): Working space depth in front of electrical equipment is 3 ft (0–150 V to ground), 3.5 ft (151–600 V), 4 ft (601–1000 V), or greater for higher voltages, based on Table 110.26(A)(1).

110.26(B): Working space must be clear and not used for storage.

110.26(C)(2): For equipment over 1200 A or over 6 ft wide, provide one entrance at each end, or a single entrance if the equipment is accessible from only one end.

110.27: Guard live parts operating at 50 V or more against accidental contact.

Article 200: Grounded conductors must be identified by white or gray finish, or by three continuous white stripes on other than green insulation.

210.52(A)(1): Receptacles must be spaced so that no point along the floor line in any wall space is more than 6 ft from a receptacle outlet.

210.52(C): Kitchen countertop receptacles: no point along the counter wall line more than 24 in. from a receptacle; at least one receptacle per island or peninsular counter space.

210.8(A): GFCI protection is required for 125-V, 15- or 20-A receptacles in dwelling unit bathrooms, garages, outdoors, kitchens, laundry areas, and within 6 ft of sinks, among other locations.

210.12(A): Arc-fault circuit-interrupter protection is required for 120-V, 15- or 20-A branch circuits supplying dwelling unit bedrooms, living rooms, and similar areas.

220.12: Lighting load for dwelling units is 3 VA per square foot; for other occupancies, use Table 220.12.

220.82: Optional feeder/service calculation for dwelling units: 100% of first 10 kVA plus 40% of remaining load, plus 100% of largest motor.

230.42: Service-entrance conductors must have ampacity not less than the load and not less than the service disconnect rating.

240.4(D): Small conductor overcurrent protection limits: 14 AWG copper-15 A; 12 AWG-20 A; 10 AWG-30 A (unless otherwise permitted).

250.52(A): Grounding electrodes include metal water pipe (10 ft or more in contact with earth), metal frame of building, concrete-encased electrode, ground ring, rod/pipe electrode, and plate electrode.

300.4: Conductors must be protected from physical damage where passing through framing members; use nail plates or bushings as required.

310.15(B)(3)(a): Adjustment factors for more than three current-carrying conductors in a raceway or cable: 4–6 conductors = 80%; 7–9 = 70%; 10–20 = 50%.

310.15(B)(2): Ambient temperature correction factors apply to conductor ampacity based on Table 310.15(B)(2)(a).

334.80: NM cable ampacity must be limited to the 60°C column of Table 310.16, and the 90°C rating may be used only for derating purposes.

352.30: PVC conduit must be supported at intervals not exceeding 3 ft, and within 3 ft of boxes and fittings.

358.30: EMT must be securely fastened within 3 ft of each box and supported at intervals not exceeding 10 ft.

376.30: Metal wireways must be supported at intervals not exceeding 5 ft and within 3 ft of each end.

404.8(A): Switches and circuit breakers must be readily accessible and installed so that the center of the grip of the operating handle is not more than 6 ft 7 in. above the floor.

406.4(D): Replacement receptacles must be GFCI-protected where required by 210.8, and tamper-resistant where required by 406.12.

422.16(B)(2): Kitchen countertop appliances may be cord-and-plug connected; the receptacle must be accessible and the cord length must not exceed 2 ft.

430.52: Motor branch-circuit short-circuit and ground-fault protection: use Table 430.52 percentages; if the standard size does not allow starting, the next higher size may be used.

430.22: Motor branch-circuit conductors must have ampacity not less than 125% of the motor full-load current.

440.32: Air-conditioning branch-circuit conductors must have ampacity not less than 125% of the rated-load current.

450.3(B): Transformer overcurrent protection: primary protection at not more than 125% of primary current for transformers over 1000 V, or as specified in Table 450.3(B).

680.26: Equipotential bonding is required for pools, including bonding of metal parts, conductive pool shells, and perimeter surfaces within 3 ft.

690.7: Maximum PV system voltage is the sum of the rated open-circuit voltages of the modules corrected for the lowest expected ambient temperature.

695.4: Fire pump disconnecting means must be installed ahead of other building loads and be marked 'Fire Pump'.

511.3: Commercial garages: areas within 18 in. of the floor are Class I, Division 2; areas above 18 in. are unclassified unless specified.

514.3: Motor fuel dispensing facilities: areas within 18 in. of the floor and within 20 ft of dispensers are classified.

517.13: Health care facilities: patient care areas require redundant grounding using an insulated copper equipment grounding conductor and a metal raceway or cable armor.

518.4: Assembly occupancies: fixed wiring must be in metal raceways or metal-clad cables, or listed plenum cables where required.

525.11: Carnivals, circuses, and fairs: receptacles must be GFCI-protected and have covers.

547.5: Agricultural buildings: equipotential planes are required in concrete slabs and at metallic water system connections.

550.4: Mobile homes: the frame must be bonded to the grounding electrode system and the equipment grounding conductor.

555.9: Marinas and boatyards: shore power receptacles must be GFCI-protected and located not less than 6 ft above the deck.

620.21: Elevator traveling cables must be supported at intervals not exceeding 6 ft and be listed for the purpose.

625.40: Electric vehicle supply equipment (EVSE) branch circuits must be supplied by a separate circuit and protected by a GFCI breaker if required.

630.11: Welding receptacle outlets must have a rating not less than the rating of the welder and be protected by a time-delay fuse or circuit breaker.

645.4: Information technology equipment rooms: disconnecting means must be provided and clearly marked.

680.22: Pool receptacles must be located not less than 6 ft from the inside wall of the pool and be GFCI-protected.

700.12: Emergency system battery capacity must be sufficient for 1.5 hours of operation at full load.

701.12: Legally required standby systems must have an alternate power source that can supply the load within 60 seconds.

702.11: Optional standby systems must have a transfer switch that prevents inadvertent interconnection with the normal supply.

700.5: Emergency systems must be capable of supplying the load for at least 1.5 hours.

701.6: Legally required standby systems must be capable of supplying the load for the duration of the outage.

702.5: Optional standby systems must be sized to supply the selected loads.

705.12(D)(2): Busbars in panelboards used for backfed power must have a rating not less than 120% of the sum of the overcurrent devices supplying them.

705.12(D)(3): The sum of the ampere ratings of all overcurrent devices on panelboards, both load and supply devices, excluding the main overcurrent device, must not exceed 120% of the busbar rating.

706.10: Energy storage systems must be listed and installed per manufacturer instructions; a disconnecting means must be provided.

708.10: Critical operations power systems (COPS) must be designed so that a single fault does not cause loss of power to the critical load.

712.10: Stand-alone systems must have a disconnecting means to isolate the system from the premises wiring.

800.24: Communications cables must be supported at intervals not exceeding 4 ft and within 12 in. of boxes.

800.110: Communications cables must be installed in raceways or be listed for the purpose; plenum cables must be used in environmental air spaces.

820.25: Coaxial cables must be bonded to the grounding electrode system using a listed grounding conductor.

830.11: Network-powered broadband cables must be listed and marked; they must not be installed in the same raceway as power conductors unless separated by a barrier.

840.4: Optical fiber cables must be listed for the application; nonconductive cables may be installed without grounding.

800.154: Communications cables must be protected from physical damage where exposed to damage.

820.100: Coaxial cable shields must be bonded to the grounding electrode system at the point of entry.

830.40: Network-powered broadband cables must be installed in accordance with Article 830 and be listed as plenum, riser, or general-purpose.

Table 310.16: Ampacities of insulated conductors rated 0–2000 V; use 60°C column for NM cable per 334.80.

Table 250.66: Grounding electrode conductor sizing based on service-entrance conductor size; for 2 AWG or smaller, use 8 AWG copper.

Table 250.122: Equipment grounding conductor sizing based on overcurrent device rating; for 15–20 A, use 14 AWG copper.

Table 430.248: Full-load currents for single-phase AC motors; use for motor branch-circuit calculations.

Table 220.42: Lighting load demand factors for dwelling units: first 3000 VA at 100%, next 117,000 VA at 35%, remainder at 25%.

Table 220.55: Demand factors for household electric ranges; for one range up to 12 kW, demand is 8 kW.

Annex D: Examples of load calculations for dwelling units and other occupancies.

Annex C: Conduit fill tables for conductors of the same size and type.

Plan review must verify that the service and feeder calculations comply with Article 220 and that conductor and overcurrent protection sizes are correct.

Check that working space around electrical equipment meets 110.26 dimensions for depth, width, and height.

Verify that all required GFCI and AFCI protections are shown on the plans for the applicable occupancies.

Confirm that grounding and bonding are detailed per Article 250, including grounding electrode conductor sizing from Table 250.66.

Ensure that the number and location of receptacles meet 210.52 spacing requirements.

Review that wiring methods are suitable for the environment (e.g., wet locations, hazardous locations) per Articles 300 and 500–516.

Check that the available fault current at the service is considered for equipment ratings (110.9 and 110.10).

Verify that the plans show the proper identification of grounded and equipment grounding conductors.