VA Electrician cheat sheet

Ohm's law: E = I × R. Power: P = E × I = I²R. Single-phase load: kW = (E × I × power factor) ÷ 1000.

A continuous load is one expected to operate at maximum current for 3 hours or more. Branch-circuit and feeder overcurrent devices are sized at 125% of the continuous load plus 100% of the noncontinuous load (NEC 210.19, 210.20, 215.3).

NEC structure: Chapters 1–4 apply generally; Chapters 5–7 supplement or modify Chapters 1–4; Chapter 9 tables and the Annexes are used as referenced, with Annexes being informational.

Dwelling receptacle spacing (210.52(A)): no point along the floor line of any wall space may be more than 6 ft from a receptacle outlet, and any wall space 2 ft or more in width requires a receptacle.

Working space (110.26): for equipment 600 V or less, at least 3 ft deep, 30 in wide, and 6 ft 6 in high, plus a dedicated equipment space above and clear of foreign piping.

Voltage drop, single phase: VD = (2 × K × I × L) ÷ circular mils, where K = 12.9 for copper and 21.2 for aluminum and L is the one-way length in feet.

GFCI protection is required for dwelling receptacles serving bathrooms, garages, outdoors, unfinished basements, and kitchen countertop areas (210.8(A)).

AFCI protection is required for dwelling branch circuits supplying outlets in bedrooms, living rooms, dining rooms, kitchens, closets, hallways, laundry areas, and similar rooms (210.12).

Standard overcurrent device ratings (240.6) include 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, and 100 amperes; where a calculated rating falls between standard sizes, the next higher standard size is generally permitted.

Nonmetallic-sheathed cable (Article 334) is permitted in dwellings and normally dry locations; it is not permitted in damp or wet locations, in masonry cavities, or in most commercial Type I/II construction above permitted heights.

NM cable support (334.30): secured at intervals not exceeding 4 ft 6 in and within 12 in of every box or fitting that does not clamp the cable.

EMT support (358.30): fastened within 3 ft of each box or termination and supported at intervals not exceeding 10 ft. Rigid metal conduit uses the same 10 ft / 3 ft pattern.

Box fill (Table 314.16(B)): 14 AWG = 2.0 in³, 12 AWG = 2.25 in³, 10 AWG = 2.5 in³ per conductor; all equipment grounding conductors together count as one volume, each device yoke counts as two volumes, and internal cable clamps count as one volume.

Minimum cover for direct-buried conductors 600 V or less (Table 300.5): 24 in general, 18 in under one- and two-family dwelling driveways, 12 in for residential 120/240 V branch circuits of 20 A or less protected by GFCI.

Raceway fill (Chapter 9, Table 1): one conductor 53%, two conductors 31%, three or more conductors 40% of the interior cross-sectional area.

A box or conduit body is required at every splice, termination, pull point, and outlet, and it must remain accessible without removing building finish (300.15, 314.29).

Conductor identification: grounded conductors white or gray (200.6); equipment grounding conductors green, green with yellow stripe, or bare (250.119).

PVC conduit requires expansion fittings where a straight exposed run is subject to significant temperature change, sized from Table 352.44.

Motor branch-circuit conductors must have an ampacity of at least 125% of the motor full-load current from Tables 430.248–430.250 (430.22).

Motor branch-circuit short-circuit and ground-fault protection is selected from Table 430.52: typically 250% of FLC for an inverse-time breaker and 175% for a non-time-delay fuse; the next standard size up is permitted if starting current trips the device, up to the table maximum.

Motor running overload protection (430.32) is separate from short-circuit protection and is based on the motor's nameplate service factor or temperature rise.

Fixed electric space-heating equipment: branch-circuit conductors and overcurrent devices are sized at 125% of the total connected load (424.3(B)).

Hermetic refrigerant motor-compressors: the branch-circuit protective device must not exceed the value marked on the nameplate as maximum fuse or circuit breaker (440.22).

Switches and circuit breakers used as switches must have their center of grip not more than 6 ft 7 in above the floor or working platform and must be readily accessible (404.8).

Single receptacle on an individual branch circuit must have an ampere rating not less than the branch-circuit rating; a receptacle on a multioutlet branch circuit must not be less than the load served (210.21(B)).

Transformers 600 V or less protected only on the primary side require primary overcurrent protection not exceeding 125% of rated primary current (Table 450.3(B)).

Hazardous location classes: Class I = flammable gases or vapors (Article 501); Class II = combustible dust (502); Class III = easily ignitable fibers or flyings (503).

Division 1 covers conditions likely to exist during normal operations; Division 2 covers conditions likely only under abnormal operation such as equipment failure or faulty operation.

In major repair garages (Article 511), the space up to 18 in above the floor is classified Class I, Division 2 because gasoline vapors are heavier than air; the area above that level is generally unclassified.

Motor fuel dispensing facilities (Article 514) use classified zones around dispensers and within 18 in of the floor to the extent shown in Figures 514.3.

Health care facilities (Article 517) require an essential electrical system with emergency and equipment branches so critical-care loads such as life-support equipment remain energized.

Swimming pools (Article 680) require an equipotential bonding grid connecting pool shells, reinforcing steel, metal fittings, and associated equipment to limit voltage gradients.

Hazardous-location equipment must be marked with its class, division or zone, and gas or dust group so that it matches the classification of the area where it is installed.

Article 700 emergency systems must be tested and maintained periodically, with written records of the tests kept on the premises.

Grounding electrodes (250.52): a rod or pipe at least 8 ft long and ½ in diameter, 20 ft of ½ in or larger rebar encased in concrete, a metal water pipe with at least 10 ft in contact with earth, and a ground ring of at least 20 ft of 2 AWG copper.

A single rod or pipe electrode must be supplemented by an additional electrode unless it has a resistance to earth of 25 ohms or less (250.53(A)(2)).

All grounding electrodes present at a building must be bonded together into a single grounding electrode system (250.50).

Grounding electrode conductor sizing, Table 250.66 (copper): 8 AWG for 2 AWG or smaller service conductors, 4 AWG for 2/0–3/0, 2 AWG for over 3/0 through 350 kcmil, 1/0 for over 350 through 600 kcmil.

Equipment grounding conductor sizing, Table 250.122 (copper): 20 A = 12 AWG, 60 A = 10 AWG, 100 A = 8 AWG, 200 A = 6 AWG, 400 A = 3 AWG.

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

A separate building or structure supplied by a feeder requires a grounding electrode system and a disconnecting means at that building (250.32).

A visible and accessible intersystem bonding termination must be provided near the service equipment for communications, CATV, and radio system grounding (250.94).

Article 800 communications circuits require a bonding conductor of at least 14 AWG copper run to the grounding electrode system, protected and as short and direct as practicable.

Electrician tradesman licenses are issued by the Virginia Department of Professional and Occupational Regulation (DPOR) through the Board for Contractors under Title 54.1 of the Code of Virginia.

Virginia issues three electrician tradesman credentials: apprentice (registered), journeyman, and master. A separate electrical contractor license is required to contract with the public for electrical work.

The Virginia Uniform Statewide Building Code adopts the National Electrical Code by reference; local building officials issue permits and perform inspections.

The Virginia Underground Utility Damage Prevention Act requires an excavator to notify the notification center (call 811 / Miss Utility) at least 2 business days but not more than 10 business days before beginning excavation.

The Board for Contractors may impose monetary penalties and suspend or revoke a license for violations, including unlicensed or improper contracting activity.

Regulated contractors must include their license number in advertising and may not use a license that has expired, been suspended, or been revoked.

Tradesman licenses are renewed on a two-year cycle, and renewal requires completion of the continuing education required by Board regulation for the specific trade.