ICC E1 cheat sheet

The E1 credential covers inspection of electrical installations for compliance with adopted codes and standards, including the National Electrical Code (NFPA 70) as locally amended.

Inspection sequence: permit and approved plans, service equipment, grounding and bonding, branch circuits and feeders, raceways and boxes, devices and fixtures, then final testing and sign-off.

Working clearances at equipment (NEC 110.26): 36 in. depth minimum for 0-150 V to ground; 42 in. for 151-600 V; width is the equipment width or 30 in., whichever is greater.

Dedicated equipment space (110.26(E)): the zone above a panelboard or switchboard up to 6 ft is reserved; no foreign piping, ducts, or leak sources permitted.

Overcurrent protection is sized to protect conductors: the conductor ampacity after adjustment and correction must be at least the next-standard-size device rating per 240.4(B) rules.

Ampacity correction: apply ambient temperature correction and conduit fill adjustment factors (310.15) to the table ampacity before comparing to the OCPD rating.

Bonding jumpers at service equipment must be sized per 250.102 (Table 250.102(C)(1)) based on the largest service conductor; equipment grounding conductors per Table 250.122 based on the OCPD rating.

Receptacle grounding and GFCI/AFCI requirements vary by location and occupancy; verify the adopted code edition before citing article numbers.

Plan review checks: load calculations, service and feeder sizing, conductor and OCPD coordination, grounding electrode system, and clearances shown on drawings.

A permit is required before installation begins; inspections are requested at defined stages (rough-in, service, final) and work must remain accessible until approved.

Approved plans must be on site and available to the inspector; field deviations require documented approval before concealment.

Records of inspection results, corrections, and re-inspection are retained by the jurisdiction; a certificate of approval or occupancy follows a passed final.

Standard calculation for a dwelling service uses Article 220 general lighting VA per square foot, small-appliance and laundry circuits, plus appliance and heating/cooling loads.

Optional method (Article 220 Part IV) uses demand factors on general loads and the larger of heating or cooling; both methods must yield a service rating adequate for the calculated load.

Correction notices must cite the specific code section and the observed condition; re-inspection verifies only the cited items plus any new visible deficiency.

Temporary power for construction requires the same grounding, GFCI protection, and overcurrent protection as permanent installations.

Conductor ampacity tables: NM-B (Romex) is limited to the 60°C column per 334.80; THHN/THWN in raceway may use the 75°C column when terminations are rated 75°C.

Box fill (314.16): each 14 AWG conductor counts 2.00 cu in., 12 AWG 2.25, 10 AWG 2.50; add one conductor count for each device yoke, clamp, and equipment grounding conductor.

Raceway fill: 1 conductor 53%, 2 conductors 31%, over 2 conductors 40% of interior cross-sectional area (Chapter 9, Table 1).

Support intervals: NM cable every 4.5 ft and within 12 in. of boxes; rigid metal conduit every 10 ft; EMT every 10 ft with no more than 360° of bends between pull points.

Bending radius and protection from physical damage: conductors in a raceway must not be damaged by bends; sleeves are required where cable passes through framing near the surface.

Wet and damp locations require listed wet-location fittings, gasketed boxes, and conductors rated for wet use (e.g., THWN-2, UF).

Separate compartments: line-voltage conductors may not share a box with Class 2/3 wiring unless the barrier or listing permits it.

Grounding electrode system: a metal underground water pipe (10 ft in contact), concrete-encased electrode, ground ring, rod/pipe electrode, and plate electrode are common electrodes; supplemental electrode required when only a water pipe is used.

Verify de-energization before touching conductors; use a listed voltage tester rated for the circuit and confirm the tester on a known live source before and after.

Continuity and polarity tests confirm grounding conductor integrity; a low-resistance reading between the grounded conductor and the grounding terminal at the service confirms the main bonding jumper.

Insulation resistance testing (megohmmeter) is a diagnostic, not typically a code pass/fail criterion; results are compared against manufacturer and baseline values.

GFCI testers simulate a ground fault; a GFCI must trip and reset, and the test button on the device itself must also operate.

Arc-fault circuit interrupter breakers require the test button to trip; AFCI protection is required for most 120 V branch circuits in dwelling units under current editions.

Stop-work authority applies when work is unsafe or unpermitted; the inspector documents the condition and notifies the permit holder in writing.

Appeals and variances follow local administrative procedure; the inspector's field decision is based on the adopted code, not on preference.

Unsafe conditions such as exposed live parts, missing covers, or improper bonding must be corrected before energization or occupancy approval.