ICC E3 cheat sheet

Article 90 establishes that the NEC is not a design manual or instruction manual; it is a minimum installation standard for safety.

The NEC is adopted by local jurisdictions; the edition in force is set by the adopting authority, not automatically by the latest published edition.

Article 100 definitions control enforcement: a "branch circuit" is the circuit conductors between the final overcurrent device and the outlet(s).

Plan review checks: service and feeder calculations, conductor sizing, overcurrent protection, grounding/bonding, box fill, and working clearances.

Chapter 1-4 rules apply generally; Chapters 5-7 modify or supplement; Chapter 9 and Annexes contain tables and informational material.

Informational Notes are explanatory only and are not enforceable requirements; only the Code text (including mandatory language) is enforceable.

Mandatory rules use "shall"; permissive rules use "shall be permitted"; "should" appears only in informational notes.

Working clearance at equipment (Table 110.26(A)(1)) is based on voltage to ground and the condition (exposed live parts on one side, both sides, or grounded surfaces opposite).

General lighting load for dwellings is 3 VA per square foot; small-appliance and laundry branch circuits are 1,500 VA each.

Standard method: apply Table 220.42 demand factors to lighting, add appliance/fixture loads, then apply the largest motor 25% adder.

Optional method (Article 220 Part IV) for dwellings uses 100% of first 10 kVA plus 40% of the remainder of the general load.

Continuous loads are calculated at 125% of the load; the overcurrent device must be at least 125% of continuous load plus 100% of noncontinuous load.

Standard ampere ratings for overcurrent devices are 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200 A, etc. (240.6).

A 20 A small-appliance branch circuit may supply receptacle outlets in kitchen, pantry, dining, and similar areas; at least two are required in a dwelling kitchen.

Receptacle outlet spacing in dwellings: no point along the wall is more than 6 ft from a receptacle; any wall space 2 ft or wider needs one.

Service conductor sizing uses Table 310.16 ampacities with adjustment (310.15) and the calculated load; the service disconnect rating must be at least the calculated load.

Grounding electrode system: metal underground water pipe (10 ft in contact), metal frame of building, concrete-encased electrode, ground ring, rod/pipe electrodes, and plate electrodes (250.52).

A single supplemental ground rod does not require a 25 ohm measurement if it is bonded to another electrode (250.53); 25 ohms applies to a single rod.

Equipment grounding conductor sizing follows Table 250.122 based on the rating of the overcurrent device protecting the circuit.

Main bonding jumper connects the grounded service conductor to the service equipment enclosure and the grounding electrode conductor at the service only.

Grounding electrode conductor sizing is in Table 250.66 and is based on the largest ungrounded service conductor.

Overcurrent devices must be sized to protect conductors per their ampacity after adjustment and correction factors (240.4, 310.15).

The next-size-up rule (240.4(B)) allows the next higher standard rating only if it does not exceed 800 A and the load does not exceed the conductor ampacity.

GFCI protection is required for dwelling bathroom, garage, outdoor, kitchen countertop, and laundry receptacles per 210.8(A) locations.

Article 500 through 506 classify hazardous (classified) locations by Class, Division/Zone, and Group; equipment must be listed for the classification.

Class I locations involve flammable gases or vapors; Class II combustible dusts; Class III ignitible fibers or flyings.

Health care facilities (Article 517) require redundant grounding and isolated/insulated grounding for critical-care patient areas.

Assembly occupancies (Article 518) and theaters (Article 520) impose requirements on emergency lighting, exit illumination, and stage wiring.

Plan review administrative provisions include permit application, approved plans and specifications, inspection scheduling, and final approval before energization.

Approved plans must show service size, feeder and branch-circuit schedules, grounding details, and load calculations; field changes require revised approval.

Equipment must be listed and labeled by a recognized testing laboratory; field-modified listed equipment may lose its listing and require re-evaluation.

Working space, dedicated equipment space (110.26(E)), and access to equipment must be shown on plans for plan review approval.