UT Electrician cheat sheet

NFPA 70 (NEC) has nine chapters: Chapters 1-4 are general, Chapters 5-7 supplement or modify them, Chapter 8 is independent, and Chapter 9 contains tables.

"Shall" indicates a mandatory requirement; "should" and Informational Notes are explanatory and not enforceable.

Annexes A through I are informational only unless a Code article specifically references them.

Article 100 definitions apply throughout the Code and are located in Chapter 1.

Under 90.4 the authority having jurisdiction interprets the Code, may grant written exceptions, and is responsible for enforcement.

Chapter 2 covers wiring and protection (Articles 200-285), Chapter 3 covers wiring methods (300-398), and Chapter 4 covers equipment for general use (400-490).

Article 110 general requirements include 110.14 terminations, 110.26 working space, and 110.28 enclosure types.

Ohm's law: V = I x R. Power: P = V x I = I squared x R = V squared / R.

Balanced three-phase power: P = 1.732 x line voltage x line current x power factor.

Single-phase voltage drop: VD = (2 x K x I x L) / circular mils; use 1.732 instead of 2 for three-phase.

K values used for voltage drop: 12.9 for copper and 21.2 for aluminum.

Dwelling general lighting load is 3 VA per square foot under Table 220.12; small-appliance and laundry branch circuits are 1,500 VA each.

Continuous loads require branch-circuit conductors and overcurrent devices at 125 percent of continuous load plus 100 percent of noncontinuous load (210.19, 210.20).

Box-fill volume per conductor (Table 314.16(B)): 14 AWG = 2.00 cubic inches, 12 AWG = 2.25, 10 AWG = 2.50.

A neutral that carries only the unbalanced current of other conductors is not counted as a current-carrying conductor (310.15(E)).

Raceway fill (Chapter 9 Table 1): one conductor 53 percent, two conductors 31 percent, more than two conductors 40 percent.

Pull box sizing (314.28): straight pulls use 8 times the largest raceway trade diameter; angle pulls use 6 times.

Support intervals: NM cable within 12 inches of a box and every 4.5 feet; EMT and rigid metal conduit every 10 feet and within 3 feet of a box.

Minimum cover (300.5): 24 inches general direct burial, 18 inches for PVC, 6 inches for rigid metal conduit, 12 inches for residential branch circuits.

A box or conduit body is required at every splice, pull point, and outlet (300.15).

300.4 requires protection from physical damage where conductors are within 1 1/4 inches of the framing surface.

Chapter 9 Table 8 lists conductor areas and Table 4 lists raceway areas for fill calculations.

Cable tray, busways, and wireways are covered by Articles 392, 368, and 376 respectively.

Receptacle spacing (210.52): no point along the floor line may be more than 6 feet from a receptacle; wall spaces 2 feet or wider are counted.

GFCI protection is required in dwelling bathrooms, garages, outdoors, kitchens, laundry areas, basements, crawl spaces, and within 6 feet of sinks.

AFCI protection is required on dwelling 120-volt branch circuits rated 20 amperes or less in bedrooms, kitchens, laundry areas, and most other rooms (210.12).

Small-conductor overcurrent limits (240.4(D)): 14 AWG = 15 amperes, 12 AWG = 20 amperes, 10 AWG = 30 amperes.

210.70 requires lighting outlets in habitable rooms, bathrooms, hallways, stairways, garages, and outdoor entrances.

Overcurrent devices must be readily accessible and may not be located in bathrooms or over steps (240.24).

Ground-fault protection of equipment (230.95) is required for solidly grounded wye services over 150 volts to ground and exceeding 1,000 amperes.

Service disconnecting means ratings are set by 230.79, with service-entrance conductors sized by Article 230 and Table 310.16.

250.50 requires all available grounding electrodes to be bonded together into a single grounding electrode system.

Common electrodes: underground metal water pipe with 10 feet of earth contact, 8-foot ground rod, concrete-encased electrode, and ground ring.

A single ground rod must show 25 ohms or less; if not, a second electrode at least 6 feet away must be added (250.53).

Grounding electrode conductors are sized from Table 250.66; equipment grounding conductors from Table 250.122.

The service neutral is grounded only at the service; panelboards downstream use a separate equipment grounding terminal bar (250.24, 408.40).

Metal water piping and structural steel must be bonded per 250.104, with bonding jumpers sized from Table 250.102(C)(1).

Equipment grounding conductors must be green, green with a yellow stripe, or bare (250.119).

250.4 requires a permanent, low-impedance ground-fault current path able to carry fault current safely.

Appliance branch circuits must have a rating not less than the appliance marked rating, and 125 percent for continuous-duty appliances (422.10).

Fixed electric space heating conductors and overcurrent devices are sized at 125 percent of the connected load (424.3).

Clothes closet luminaires: 12 inches of clearance for surface-mounted incandescent, 6 inches for recessed incandescent (410.16).

Transformer overcurrent protection is set by 450.3, and 450.14 requires a disconnecting means for transformers.

Panelboards require overcurrent protection not greater than the panelboard rating (408.36).

Receptacles in wet or damp locations must be listed weather-resistant types with in-use covers where required (406.9).

Flexible cords and cables (Article 400) may not be used as a substitute for the fixed wiring of a structure.

Motor full-load current for conductor and short-circuit protection comes from Tables 430.247-430.250, not the nameplate; nameplate current is used for overload sizing.

Motor branch-circuit conductors must have ampacity of at least 125 percent of the motor full-load current (430.22).

430.52 short-circuit protection: inverse-time breaker 250 percent, dual-element fuse 175 percent, non-time-delay fuse 300 percent of full-load current.

430.32 overload protection: 125 percent of nameplate current for motors with a 1.15 service factor, otherwise 115 percent.

The motor disconnecting means must be within sight of both the motor and the controller (430.102).

Several motors on one branch circuit: 125 percent of the largest full-load current plus the sum of the others (430.24).

Hermetic refrigerant motor-compressors: conductors at 125 percent and overcurrent protection at 175 percent, up to 225 percent, of rated load current (440.32, 440.22).

Motor control circuits are covered in Article 430 Part VI; remote-control circuits are Class 1 circuits under Article 725.

Class I locations contain flammable gases or vapors, Class II locations contain combustible dust, and Class III locations contain ignitable fibers or flyings (Article 500).

Division 1 means the hazard exists under normal conditions; Division 2 means the hazard exists only under abnormal conditions.

Articles 505 and 506 provide the Zone classification system as an alternative to divisions for Class I locations.

Seals are required in conduit leaving Class I, Division 1 enclosures (501.15).

Article 517 covers health care facilities, where critical care areas require hospital-grade receptacles and redundant grounding.

Article 511 covers commercial garages, Article 514 motor fuel dispensing facilities, and Article 555 marinas and boatyards.

Article 700 covers emergency systems, Article 701 legally required standby, Article 702 optional standby, and Article 708 critical operations power systems.

Pools and spas (Article 680): equipotential bonding with at least 8 AWG copper, and receptacles GFCI protected and at least 6 feet from the water edge.

Solar photovoltaic systems (Article 690): short-circuit current is multiplied by 125 percent for conductor and overcurrent device sizing, and rapid shutdown is required.

Fire pumps (Article 695): the overcurrent device must carry the locked-rotor current indefinitely.

Energy storage systems are Article 706 and electric vehicle charging is Article 625.

Temporary wiring is Article 590; it must be removed after construction and temporary receptacles require GFCI protection.

Interconnected electric power production sources are Article 705, and signs and outline lighting are Article 600.

Cranes and hoists, electric welders, and induction heating equipment are covered by Articles 610, 630, and 665.

Articles 725, 760, 770, 800, 820, and 830 cover Class 1/2/3 circuits, fire alarm, optical fiber, communications, CATV/radio, and broadband systems.

Class 2 and Class 3 circuits are power-limited; permitted power sources are listed in Chapter 9 Tables 11(A) and 11(B).

Class 2 and Class 3 conductors generally may not occupy the same raceway, cable, or enclosure as power conductors (725.136).

Communications cables must be separated from power conductors by at least 2 inches where not in raceways (800.133).

Fire alarm Class A circuits continue operating after a single open or ground fault; Class B circuits do not.

Fire alarm cable must be listed for the purpose and installed per the permitted Chapter 3 or cable methods of Article 760.

Low-voltage lighting systems are limited to 30 volts or less and require listed power supplies (Article 411).

The Utah Electricians Licensing Act is administered by the Division of Occupational and Professional Licensing (DOPL) within the Department of Commerce.

Administrative rule R156-55b implements the Electricians Licensing Act and establishes licensing and renewal requirements.

License categories include apprentice, journeyman, master, residential journeyman, and residential master electrician.

Electrical work must be performed under a licensed electrical contractor, and a permit must be obtained from the local building authority before work begins.

Local jurisdictions inspect electrical installations and may require correction of Code violations before the work is energized.

Apprentices must be registered with DOPL and work under the supervision of a journeyman or master electrician.

DOPL may deny, suspend, revoke, or place a license on probation for Code violations, incompetence, or dishonest dealing.

Utah adopts the National Electrical Code by administrative rule; the edition in effect applies to permits issued while it is in force.