- Which 2A This Guide Covers
- Exam Mechanics: Format, Fee, Calculator and References
- The Code Edition Question to Settle First
- Where the 50 Questions Come From
- Domains 6, 9, 4 and 5: Where Most Points Live
- Domains 2 and 3: Few Questions, High Precision
- Domains 1, 7 and 8: The Supporting Areas
- Building an Open-Book Reference System
- A Domain-Weighted Study Path
- After the Exam: Credentials, Reciprocity and Employers
- Frequently Asked Questions
- The exam is 50 open-book, four-option multiple-choice questions in two hours, with a cut-score of 70 and a USD 130 fee per attempt.
- Confirm the NEC edition for your booked exam with Prov before buying code books; the bulletin's edition labels conflict.
- Wiring Methods and Service Equipment each carry nine questions, so together they account for 18 of the 50 items.
- Calculations of Load and Wire Size total only five questions, but every miss there is an arithmetic or table-lookup error you can prevent.
Which 2A This Guide Covers
The label "2A" appears on several unrelated credentials. This guide covers exactly one: the Electrical Inspector One- and Two-Family Dwellings (2A) examination, a legacy IAEI-associated exam in the NCPCCI (National Certification Program for Construction Code Inspectors) family. It tests residential electrical inspection knowledge, meaning the codes and installations found in single-family homes and duplexes. If you want the plain-language definition first, see What Is 2A? or What Is 2A Certification?.
A few distinctions matter before you spend any money:
- IAEI and the Independent Alliance of the Electrical Industry: IAEI now does business under the Independent Alliance name as a DBA. An older candidate bulletin named IAEI as a partner on this exam; the current bulletin keeps the 2A exam but omits IAEI from its partner list. The exam specifications do not, by themselves, establish current IAEI credential issuance or renewal.
- ICC E1: A separate ICC credential. ICC does offer a transition route for NCPCCI 2A holders, covered later in this guide.
- CEI-R: IAEI's residential certification route. Its practicum and examination rules are separate and do not define the 2A exam. Some marketplace study listings blur the two, so verify any "2A" product against the nine official subject areas below.
- Local licenses: Passing the exam does not confer a local license or certification on its own.
The exam is administered by Prov, with testing centers and ExamRoom.AI remote proctoring. NCPCCI imposes no prequalifications to sit for it, which is why 2A requirements are really about your jurisdiction and employer, not the exam registration.
Exam Mechanics: Format, Fee, Calculator and References
| Item | Detail |
|---|---|
| Delivery | Computer-based, at a testing center or via ExamRoom.AI remote proctoring |
| Questions | 50, four-option multiple choice |
| Time | Two hours |
| Book policy | Open book; approved references only |
| Cut-score | 70 |
| Fee | USD 130 per attempt, retakes included |
| Retake wait after a failure | 30 days |
| Calculator | On-screen, includes square root |
Two hours for 50 questions averages 2.4 minutes per item. That sounds generous until you remember it is an open-book exam: the clock is mostly spent flipping, locating and cross-checking, not recalling. Questions that look like a quick table lookup can eat five minutes if your book is not tabbed. For the scoring details, read 2A passing score; for the full cost picture including study purchases kept separate from exam fees, see 2A certification cost.
Approved reference books may be highlighted and permanently tabbed before testing, and the applicable NEC Handbook is permitted. Other editions of the same reference title may be brought, but the specified edition governs answers. That last sentence is the reason the next section exists.
The Code Edition Question to Settle First
Candidates routinely buy the wrong book. The Prov candidate bulletin (printed version 2024.03.12) lists code forms in a way that is not fully consistent:
- The 2017 Code form lists the 2017 NEC and the 2018 IRC.
- A newer listed form is labelled 2A (2021 Code) and specifies the 2021 IRC.
- Its NFPA 70 reference contains conflicting 2017/2020 wording, and the ISBN given (9781455922970) corresponds to the 2020 NEC, a mapping corroborated by Cengage's product listing for the National Electrical Code 2020 and by the NEC 2020 label elsewhere in the same bulletin.
That title conflict is unresolved in the bulletin itself. The practical rule: before choosing code-specific preparation materials, confirm the NEC edition for your booked examination directly with Prov. Get the answer in writing if you can.
Code-edition drift matters most in the domains where article numbers, table locations or requirements move between editions, which is another reason to practice with the edition you will actually carry into the room. The IRC is part of the picture too: electrical chapters and cross-references in the residential code are fair game, so your reference stack needs to cover both documents. A broader treatment of format and difficulty is in How Hard Is the 2A Exam?.
Where the 50 Questions Come From
The bulletin publishes item counts, not percentage weights, and we do not convert them into percentages here. The official allocations, in domain order:
| Domain | 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 |
These nine headings are official exam subject areas, not a preparation curriculum, so they tell you what is tested, not how to learn it. Note that some third-party course pages list building-inspection subjects instead of these electrical ones; trust the nine above. A deeper domain-by-domain breakdown lives in the 2A exam domains guide.
The arithmetic is useful. Domains 6 and 9 hold nine questions each, Domain 4 holds eight, and Domains 1 and 5 hold six each. Those five areas total 38 of 50 items. The three smallest domains (2, 3 and 8) together hold only seven.
Domains 6, 9, 4 and 5: Where Most Points Live
Domain 6: Service Equipment and Conductors on the Supply Side of the Service (9 questions)
This is a residential inspector's bread and butter: everything from the utility connection through the service disconnect.
- Service entrance conductor sizing, rating and permitted wiring methods
- Service disconnect location, grouping and maximum number of disconnects
- Grounding electrode system, grounding electrode conductors and bonding at the service
- Meter socket and service equipment clearances, working space and mounting
- Overhead service clearances, mast support and weatherhead details
Domain 9: Wiring Methods (9 questions)
Expect scenario questions asking which method is permitted where, how it must be supported and protected, and what limits apply.
- Nonmetallic-sheathed cable: support, securing, protection through framing members, and bending radius
- Metal and nonmetallic conduit and tubing: permitted locations, fill, bends, supports and expansion
- Underground installations: cover depth tables and where they change by method and circuit type
- Damp, wet and exterior locations, and which methods and fittings qualify
- Fire-stopping and penetration requirements where wiring passes through framing or separations
Domain 4: Conductors and Overcurrent Protection on the Load Side of the Service (8 questions)
Branch circuits, feeders and the devices that protect them, applied the way a rough-in inspection would apply them.
- Branch-circuit ratings, required circuits and receptacle outlet spacing in dwelling units
- Conductor ampacity, correction and adjustment factors, and terminal temperature limits
- Overcurrent device ratings, standard sizes and the small-conductor limits
- Ground-fault and arc-fault protection requirements by room and circuit type
- Feeder and subpanel requirements, including grounding and neutral separation
Domain 5: Lighting and Utilization Equipment (6 questions)
This area spans fixtures, appliances and the equipment homeowners actually plug in or hard-wire.
- Luminaire location, clearances and support in closets, bathrooms and wet locations
- Appliance circuit and disconnecting means requirements
- Motor, water heater, HVAC and similar fixed-equipment branch-circuit rules
- Receptacle and ceiling-fan outlet box support and listing requirements
When you drill these domains, practice by topic and by article. After each missed question, write down the article number and the sentence that settles it, not just the answer. Our 2A practice tests are organized so you can target exactly these areas.
Domains 2 and 3: Few Questions, High Precision
Calculations of Load and Calculations of Wire Size carry two questions each. That makes them easy to underestimate and easy to lose points on, because there is no partial credit and a single rounding or table error flips the whole answer. The on-screen calculator includes square root, which suggests the exam expects multi-step math in at least some items.
What to practice:
- Standard dwelling load calculations: general lighting load by square footage, small-appliance and laundry circuits, demand factors, and how fixed appliances and the largest motor or heating/cooling load enter the total.
- Service and feeder sizing from a computed load: convert volt-amperes to amperes correctly and choose the next standard size per the edition you are using.
- Conductor ampacity selection: apply temperature ratings, ambient correction and conductor-count adjustment in the right order.
- Voltage drop and wire sizing: keep your formula and units consistent, and check whether the question asks for a requirement or a recommendation.
Domains 1, 7 and 8: The Supporting Areas
Domain 1: Cabinets, Panelboards, Switchboards, Boxes, and Conduit Bodies (6 questions)
Six questions reward careful reading of enclosure and box rules.
- Box fill calculations: conductor volume allowances, device and clamp deductions, and the volume of the box you are checking against
- Box support, mounting flush with finished surfaces, and accessibility
- Panelboard rules: working space, dedicated space, overcurrent device limits, and unused openings
- Conduit body fill and permitted splices
Domain 7: Special Installations or Constructions (5 questions)
This grab-bag area covers residential installations with their own rules.
- Swimming pools, spas and hot tubs: bonding, clearances and GFCI protection
- Pre-wired smoke and carbon monoxide alarm power and interconnection as referenced through the residential code
- Generators, transfer equipment and standby systems at the dwelling
- Solar photovoltaic and energy storage basics as they appear in one- and two-family settings
Domain 8: Switches, Disconnects and Controllers (3 questions)
The smallest domain, but the questions tend to be direct application of a specific rule.
- Switch ratings, grounding at switch locations and neutral availability
- Disconnect location and lock-capability requirements for equipment
- Appliance and motor controller basics
Do not neglect these three domains because of their smaller counts. Fourteen questions across Domains 1, 7 and 8 is more than a quarter of the exam, and a few of those items are among the more predictable ones. For a quick refresher on the facts you should be able to recall without searching, keep the 2A cheat sheet nearby.
Building an Open-Book Reference System
Open book does not mean easy. It means the test measures whether you can find and apply the right provision quickly. Because approved references may be highlighted and permanently tabbed before testing, preparation of the books themselves is part of studying.
What to tab and mark
- The article and chapter dividers for the code book, so you can jump straight to the right area
- Every table you touch in Domains 2 and 3: conductor ampacities, correction factors, adjustment factors, box fill volumes, conductor dimensions and demand-factor tables
- The service, grounding and bonding articles for Domain 6
- The wiring-method articles for Domain 9, with distinct tab colors for different method families
- Any IRC electrical chapter sections you rely on for dwelling-specific requirements
Rules for the reference-handling day
- Confirm the permitted-references list and tabbing rules in the bulletin's reference appendix before you mark anything permanently.
- Use the edition the exam specifies, since the specified edition governs answers even if you carry another.
- Rehearse on the same marked books you will bring so that finding a table is muscle memory, not a search.
Key Takeaway
Time yourself locating provisions, not just answering questions. If a lookup takes more than about two minutes on a practice item, your tabbing or index habits need work. Fix the system, then add volume.
A Domain-Weighted Study Path
This is the one structured study schedule in this guide. It is ordered by how many questions each domain carries and by how much groundwork later domains depend on. Adjust the length to your experience; an inspector who already does residential plan review will compress it, while someone new to inspection may stretch it.
Orientation and reference setup
- Confirm the NEC edition with Prov and obtain the matching code book and IRC
- Read the bulletin's subject outline and reference rules; tab your books
- Take one untimed diagnostic to see which domains cost you the most lookups
Domain 6 and Domain 9
- Work service equipment, grounding and bonding end to end
- Drill wiring-method selection, support and protection scenarios
- These two domains hold 18 of the 50 questions
Domain 4 and Domain 5
- Branch circuits, ampacity adjustments and overcurrent protection
- Luminaires, appliances and fixed equipment rules
- Log every missed item by article number
Domains 2 and 3, then 1, 7 and 8
- Full load calculation and wire-sizing problems with every step written out
- Box fill, panelboard and enclosure rules
- Special installations and switch/disconnect provisions
Timed full-length rehearsal
- Sit 50 questions in two hours on your marked books
- Review every miss for cause: knowledge gap, lookup failure or arithmetic slip
- Book the exam once timed results are consistently above the cut-score of 70
Because retakes cost the full USD 130 and require a 30-day wait, it is cheaper to extend preparation by a week than to rush a first attempt. Use the 2A practice test for the timed rehearsal, and review scheduling details in 2A exam dates. For the broader prep landscape, see 2A training.
After the Exam: Credentials, Reciprocity and Employers
A passing score is a credential input, not a finished license. Treat the post-exam phase as its own checklist.
The ICC E1 transition route
ICC's NCPCCI reciprocity page (updated November 6, 2025) permits an E1 transition application using NCPCCI 2A. You need three things: your 2A score report, supporting documentation, and a current license. The transition carries a separate fee and is subject to ICC approval, so it is neither automatic nor included in the USD 130 exam fee.
A short checklist before you act
- Ask your jurisdiction or employer whether they accept NCPCCI 2A on its own, or require a local license or other certification.
- Keep your score report; it is the supporting document for any transition application.
- If you are considering ICC E1 or IAEI's CEI-R, treat each as a separate route with its own fees and rules, and research renewal requirements for your chosen route independently rather than assuming 2A rules carry over.
- Budget exam fees, study materials, and any transition or application fees as distinct line items.
Employers who hire residential electrical inspectors include municipal and county building departments, third-party inspection and plan-review firms, and insurance or code-consulting organizations. Acceptance of the credential varies by jurisdiction, so confirm before booking. For career context, see 2A jobs, 2A salary guide and Is the 2A certification worth it?. Keep in mind that occupation-wide salary information describes the inspection field broadly and does not isolate the effect of holding this one credential.
If you are comparing credentials, the 2A certification overview explains where this exam fits.
Frequently Asked Questions
Yes. Approved reference books are permitted, and they may be highlighted and permanently tabbed before testing. The applicable NEC Handbook is also permitted. Check the bulletin's reference appendix for the current approved list before you mark your books.
The exam has 50 four-option multiple-choice questions and a two-hour time limit, delivered by computer. You need a score of 70 to meet the official cut-score.
The exam fee is USD 130 per attempt, and that includes retakes. After a failed attempt you must wait 30 days before retesting. Study materials, transition applications and any local licensing fees are separate costs.
Confirm the edition for your booked exam directly with Prov before buying code books. The candidate bulletin lists a 2017 form and a 2021 Code form, and its NFPA 70 wording conflicts between 2017 and 2020. The specified edition governs the answers, so do not assume.
No. Passing alone does not confer a local license or certification. Check your jurisdiction's requirements, and see 2A requirements for how eligibility and acceptance work in practice.
For a final self-check, take a timed run on the 2A practice exam and compare your results against the domain table above to decide where to spend your last study hours.