- Which 2A This Guide Covers
- The Nine Domains and Their Question Counts
- The Heavy Domains: Wiring Methods, Supply-Side Service, Load-Side Protection
- Domains 2 and 3: Few Questions, High Stakes
- Enclosures, Utilization Equipment, Switches and Special Installations
- The NEC Edition Question
- Working an Open-Book, 50-Question Exam
- Sequencing Your Preparation by Domain
- What the Score Does and Does Not Do
- FAQ
- The exam has 50 four-option questions across nine official subject areas, with two hours allowed and a cut-score of 70.
- Wiring Methods and Service Equipment (supply side) carry nine questions each; load-side conductors and overcurrent protection carry eight.
- The bulletin publishes item counts, not percentage weights, so study time should follow question counts directly.
- Confirm the NEC edition for your booked form with Prov before buying code books; the bulletin's reference titles conflict.
Which 2A This Guide Covers
The acronym "2A" is used by several unrelated credentials. This guide covers only one: the Electrical Inspector One- and Two-Family Dwellings (2A) examination, the legacy IAEI-associated NCPCCI exam for residential electrical inspectors. IAEI (the International Association of Electrical Inspectors, now doing business as the Independent Alliance of the Electrical Industry) was named as a partner in an earlier Prov bulletin edition. The current bulletin keeps the exam but omits IAEI from its partner list, so do not assume IAEI currently issues or renews the credential. If you are still sorting out terminology, our explainers on what 2A is and what 2A stands for cover the naming.
The exam is currently administered by Prov through testing centers and ExamRoom.AI remote proctoring. It is computer-based and open book, with four-option multiple-choice questions. You get two hours for 50 questions, and the official cut-score is 70. NCPCCI imposes no prequalifications to sit for it (see 2A requirements), though passing alone does not confer a local license or certification.
Everything about the domain list comes from the Prov NCPCCI Candidate Information Bulletin (printed version 2024.03.12), where the exam outline appears on page 5. The nine headings below are official exam subject areas, not a curriculum. They tell you what is tested, not how to learn it.
The Nine Domains and Their Question Counts
The bulletin lists the domains in the order below and assigns each an item count. It does not publish percentage weights, and none are derived here. The counts add up to the full 50 questions.
| Domain | Official Subject Area | Questions |
|---|---|---|
| 1 | Cabinets, Panelboards, Switchboards, Boxes, and Conduit Bodies | 6 |
| 2 | Calculations of Load | 2 |
| 3 | Calculations of Wire Size | 2 |
| 4 | Conductors and Overcurrent Protection on the Load Side of the Service | 8 |
| 5 | Lighting and Utilization Equipment | 6 |
| 6 | Service Equipment and Conductors on the Supply Side of the Service | 9 |
| 7 | Special Installations or Constructions | 5 |
| 8 | Switches, Disconnects and Controllers | 3 |
| 9 | Wiring Methods | 9 |
Three domains (4, 6 and 9) account for 26 of the 50 questions, more than half the exam. The two calculation domains together account for only four. Many candidates fear the math most, yet the heaviest scoring opportunity is in installation requirements. The same structure shows up in our discussion of how hard the 2A exam is.
The Heavy Domains: Wiring Methods, Supply-Side Service, Load-Side Protection
Domain 9: Wiring Methods (9 questions)
Tied for the largest domain. In a one- and two-family dwelling, this is the daily substance of rough-in and final inspections.
- Which wiring methods are permitted in which locations, and where the limits fall (damp, wet, exposed, concealed, underground, attic and crawl-space conditions)
- Support, securing and protection requirements, including distances from boxes and protection from physical damage
- Installation rules that follow from the chosen method, such as bending, fill and splicing practices
- How the IRC's electrical chapters point back to the NEC, since the exam involves both code sets
Domain 6: Service Equipment and Conductors on the Supply Side of the Service (9 questions)
Everything between the utility connection and the main disconnect. Inspectors see this work at the start and end of every dwelling project.
- Service conductor types, sizing considerations and installation rules
- Service equipment location, disconnecting means and working clearances
- Grounding electrode system and bonding at the service
- Where supply-side rules end and load-side rules begin, a boundary the exam uses to separate Domains 4 and 6
Domain 4: Conductors and Overcurrent Protection on the Load Side of the Service (8 questions)
Branch circuits and feeders downstream of the service, with the overcurrent devices that protect them.
- Branch-circuit requirements for dwelling units, including required circuits and ratings
- Overcurrent protection rules, including conductor protection and device ratings
- Ground-fault and arc-fault protection requirements for dwelling locations
- Feeder and branch-circuit conductor selection as it connects to Domain 3's calculations
These three domains reward navigation skill more than memorization. The question usually describes an installation and asks whether it complies, or which rule governs. If you can locate the right article quickly, you can answer from the book. For a wider view of how the nine areas fit into one plan, see the 2A study guide.
Domains 2 and 3: Few Questions, High Stakes
Calculations of Load and Calculations of Wire Size carry two questions each. Do not skip them, but do not let them consume your preparation either. Since the exam is open book and the on-screen calculator includes a square root function, the challenge is knowing which method applies and following it without arithmetic slips.
Domain 2: Calculations of Load
- Standard dwelling-unit load calculation steps: general lighting and receptacle load, small-appliance and laundry circuits, then demand factors
- Fixed appliances, cooking equipment, dryers and heating or cooling loads in the calculation
- The difference between the standard method and optional methods, and when each is used
- Translating a calculated load into a service or feeder size
Domain 3: Calculations of Wire Size
- Selecting conductor size from ampacity tables with the correct temperature column
- Applying ambient-temperature correction and bundling adjustment where the scenario calls for it
- Terminal temperature limits that cap the usable ampacity
- Continuous-load multipliers and how they affect the minimum conductor and overcurrent device
Enclosures, Utilization Equipment, Switches and Special Installations
Domain 1: Cabinets, Panelboards, Switchboards, Boxes, and Conduit Bodies (6 questions)
The physical side of the electrical system: enclosures and the rules for what goes in them.
- Box fill calculations and the volume allowances for conductors, devices, clamps and fittings
- Panelboard installation, including working space, circuit directories and arrangement
- Where boxes and cabinets must be placed, secured and made accessible
- Conduit body fill and use rules
Domain 5: Lighting and Utilization Equipment (6 questions)
Equipment that consumes power, installed in dwellings.
- Luminaire installation rules by location, including clearances and wet or damp area requirements
- Recessed lighting and insulation contact considerations
- Appliance and fixed-equipment installation, including disconnecting means and cord connections
- Receptacle placement and tamper-resistance in dwelling locations
Domain 7: Special Installations or Constructions (5 questions)
Topics that sit outside the standard branch-circuit framework and carry their own rules.
- Swimming pools, spas and hot tubs, with their bonding and distance requirements
- Solar photovoltaic systems, energy storage and similar newer residential technologies
- Generators and standby power arrangements
- Other special occupancies and equipment that apply to dwellings
Domain 8: Switches, Disconnects and Controllers (3 questions)
The smallest equipment domain, but the questions are often straightforward lookups if your references are tabbed.
- Switch installation, ratings and location requirements
- Disconnecting means for motors, appliances and equipment
- Controller and motor-related requirements that appear in residential contexts
Domains 1, 5, 7 and 8 together total 20 questions. They are narrower in scope than the three heavy domains but reward careful reading, because small details such as location, voltage or equipment type often decide which rule applies. If a question hinges on an unfamiliar term, check the definitions in the code book rather than guessing.
The NEC Edition Question
Before you buy a code book, resolve a documentation conflict. The Prov bulletin describes more than one form of this exam. The 2017 Code form lists the 2017 NEC and 2018 IRC. A newer listed form is labelled 2A (2021 Code) and specifies the 2021 IRC. For the NEC, the bulletin's NFPA 70 reference contains conflicting 2017/2020 wording, and the ISBN it lists (9781455922970) corresponds to the 2020 NEC, as labelled elsewhere in the same bulletin and corroborated by an indexed Cengage product listing. The title conflict remains unresolved.
This matters because rules shift between NEC editions, especially around protection requirements, working-space provisions and newer technologies. Using the wrong edition for practice can train you toward answers the exam will not accept. The cost implications of books and retakes are laid out in the 2A certification cost breakdown.
Working an Open-Book, 50-Question Exam
Two hours for 50 questions gives you an average of just over two minutes each. That is generous if you know where to look, and tight if you are reading the code cover to cover during the exam. Approved reference books may be highlighted and permanently tabbed before testing, and the applicable NEC Handbook is permitted. Check the reference-rules appendix in the bulletin (PDF page 22) for exactly what is allowed before you finalize your tabbing.
- Tab by domain, not by chapter number. Mark the tables and articles you will use for the nine-question domains first: wiring method articles, service and grounding provisions, branch-circuit and overcurrent rules.
- Tab the IRC alongside the NEC. The exam involves both code sets, and the IRC's electrical chapters cross-reference the NEC.
- Mark the calculation tables. Ampacity, demand factors, box fill volumes and conduit fill tables should each have a visible tab.
- Answer known questions first. Flag the ones that need a long lookup and return to them with time remaining.
Key Takeaway
Open book does not mean easy. It means the test rewards speed of retrieval. Practice finding answers in your tabbed books under a two-hour clock, then review every miss to see whether the problem was knowledge, navigation or misreading. For more on reading the cut-score, see 2A passing score.
Sequencing Your Preparation by Domain
Rather than a generic schedule, order your study by question counts and by dependencies between domains. Calculation domains rely on tables and definitions you will already have tabbed, so they work well once your navigation is solid.
Wiring Methods (Domain 9) and Boxes (Domain 1)
- Work through permitted methods and installation rules
- Practice box fill with the tables you will use on exam day
- Tab your books as you go
Service Equipment (Domain 6) and Load-Side Protection (Domain 4)
- Trace the path from utility to main disconnect to branch circuits
- Drill the boundary between supply-side and load-side rules
- Review arc-fault and ground-fault protection locations
Calculations (Domains 2 and 3)
- Build written procedures for load and conductor sizing
- Practice with the on-screen calculator style, including square root
Equipment, Special Installations and Timed Review (Domains 5, 7, 8)
- Cover utilization equipment, pools, solar and switch rules
- Sit a full 50-question timed run and log every miss by domain
Adjust the pace to your background. A working electrician may move faster through installation domains and spend longer on code-edition navigation, while a newcomer may reverse that. A broader plan appears in the 2A study guide, and the 2A cheat sheet works as a final-days refresher. Timed drills are available on the main practice site.
What the Score Does and Does Not Do
The exam fee is USD 130 per attempt, and that includes retakes. After a failed attempt you must wait 30 days before retesting. Keep this fee separate in your budget from study materials and from any later certification or license applications.
Passing alone does not confer a local license or certification. Whether a jurisdiction or employer accepts the result depends on local rules, so confirm with the authority you plan to work under. Our guides to 2A jobs and the value of the credential go deeper on employer acceptance.
| Item | What the Sources Support |
|---|---|
| Exam fee | USD 130 per attempt, retakes included |
| Retake wait | 30 days after a failed attempt |
| Prerequisites | None imposed by NCPCCI to sit the exam |
| Local licensing | Passing does not by itself confer a license or certification |
| ICC transition | ICC's reciprocity page (updated November 6, 2025) allows an E1 transition application using NCPCCI 2A, a supporting score report and a current license, with separate fee and approval |
| Pass rate | No authoritative current pass rate verified; the cut-score of 70 is not a pass-rate statistic |
The ICC E1 transition and IAEI's separate CEI routes are different pathways. CEI residential rules do not define the 2A exam, so keep them apart when researching renewals or next steps. For pass-rate context, see 2A pass rate, and for pay questions, the 2A salary guide.
FAQ
In domain order: Cabinets, Panelboards, Switchboards, Boxes, and Conduit Bodies has 6; Calculations of Load has 2; Calculations of Wire Size has 2; Load-Side Conductors and Overcurrent Protection has 8; Lighting and Utilization Equipment has 6; Service Equipment and Supply-Side Conductors has 9; Special Installations or Constructions has 5; Switches, Disconnects and Controllers has 3; and Wiring Methods has 9. The total is 50.
Wiring Methods and Service Equipment and Conductors on the Supply Side of the Service each have nine questions, followed by load-side conductors and overcurrent protection with eight. Together those three account for 26 of 50 questions, so they deserve the largest share of study time.
Yes. Approved reference books may be highlighted and permanently tabbed before testing, and the applicable NEC Handbook is permitted. The exam is computer-based with four-option multiple-choice questions, 50 questions in two hours, and an on-screen calculator that includes square root. Check the bulletin's reference-rules appendix for the exact permitted items.
Confirm with Prov for the exact form you booked. The bulletin lists a 2017 Code form (2017 NEC and 2018 IRC) and a newer 2A (2021 Code) form specifying the 2021 IRC, while its NFPA 70 reference shows conflicting 2017/2020 wording and an ISBN tied to the 2020 NEC. The title conflict is unresolved, and the specified edition governs answers.
The fee is USD 130 per attempt, including retakes. If you do not reach the cut-score of 70, you must wait 30 days before retesting. See the 2A certification cost guide for how exam fees fit alongside study purchases and other charges.