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Oklahoma Limited Electrical Contractor — Practice Exam

What This Practice Exam Covers

The Oklahoma Limited Electrical Contractor licensing exam is 100 questions with a 240-minute time limit. You need a 70% (70 correct) to pass. The exam draws from 13 topic areas covering NEC code requirements, electrical theory, safety regulations, and installation practices specific to Oklahoma.

This site offers two ways to practice:

Free practice exam: Every attempt gives you 10 questions pulled from a limited pool. You can retake it as many times as you want — useful for getting familiar with the question style and format before committing to serious prep.

Full practice exam (paid): Mirrors the real exam exactly — 100 questions, 240-minute timer, same topic proportions. Questions are drawn from a pool of 707+ items, so every attempt produces a unique exam. No two sessions are identical, which means repeated attempts continue building knowledge rather than rewarding memorization of a fixed set.

Start with the free exam to calibrate where you stand, then use the full exam to prepare systematically.

What You'll Be Tested On

General Knowledge (5 items) covers permits, inspections, preservation of structural integrity during installation, and needs analysis with estimating. Expect questions about when permits are required, what inspectors verify, and how to scope a job correctly.

General Electrical Knowledge (4 items) is calculation-heavy for its size. You must solve voltage, current, and resistance in series, parallel, and combination circuits — including the formulas in Ugly's Electrical References (Pages 1–2, 3–4, 5–7). Power used in a circuit, power lost as heat, cost of power, and both single-phase and three-phase AC theory are all testable. Know your Ohm's law variants cold and be comfortable with three-phase multipliers.

Electrical Installation Requirements (6 items) tests approved installation methods for standard voltage equipment and systems exceeding 600 volts. Questions typically ask whether a specific installation method is permitted in a given location, referencing NEC 235-series requirements (NEC 235.202(B), NEC 235.404(A), NEC 235.411, NEC 235.412).

Services, Feeders, and Branch Circuits (5 items) covers service entrance rules (NEC 230.2, NEC 230.24(A), NEC 230.24(B), NEC 230.26), voltage drop calculations for branch circuits and feeders (NEC 210.19 Informational Note; NEC 215.2(A)(2) Informational Note No. 2), outside branch circuits and feeders (NEC 225.18, NEC 225.39(C), NEC 225.39(D)), and feeder sizing (NEC 215.2(A)(1), NEC 215.4(A)).

Overcurrent Protection (4 items) focuses on NEC overcurrent rules: where protection must be located (NEC 240.24(A), NEC 240.24(B)(1), NEC 240.24(B)(2)), tap conductor rules (NEC 240.21(B)(1), NEC 240.21(B)(2)), conductor protection (NEC 240.4(A), NEC 240.4(D)(4), NEC 240.4(D)(6)), and fuse and breaker ratings from NEC 240.4(B) and Table 240.6(A).

Grounding and Bonding (10 items) is one of the two largest topic areas. You must know general requirements (NEC 250.4(A)(5), NEC 250.12), main bonding jumper sizing (NEC 250.28(B), NEC 250.28(D)(1)), grounding electrode conductor sizes, equipment grounding conductor sizes, and separately derived system grounding (NEC 250.30(A)(5), NEC 250.30(A)(6)(a)(1)). Disconnected building/structure grounding rules under NEC 250.32(A) and NEC 250.32(B)(1) appear regularly.

Conductors and Cables (10 items) — tied for the largest topic — covers underground conductor rules (NEC 338.10(B)(4)(a)(2)), vertical installation support, conductor selection from NEC Table 310.4(1) and Table 310.16, armored cable Type AC (NEC 320.12, NEC 320.24), metal-clad cable Type MC (NEC 330.24(B), NEC 330.30(B)), and nonmetallic-sheathed cable Types NM/NMC/NMS (NEC 334.10(A), NEC 334.12(A)(9), NEC 334.30).

Raceways and Boxes (9 items) covers box fill calculations (NEC Table 314.16(B)(1)), pull box sizing (NEC 314.28(A)(1), NEC 314.28(A)(2)), rigid metal conduit — Type RMC (NEC 344.24(B), NEC 344.60), electrical metallic tubing — Type EMT (NEC 358.12, NEC 358.28(B)), flexible metal conduit — Type FMC (NEC 348.12, NEC 348.30(A)), and PVC conduit expansion (NEC 352.44(A) and Table 352.44(A)).

Special Occupancies and Equipment (10 items) tests hazardous location classifications (NEC 500.5(B), NEC 500.5(C), NEC 500.5(D)(1)(b), NEC 500.6(A)(4)), Class I wiring methods (NEC 501.10(A)(1)(2), NEC 501.15(A)(1)), Class II requirements (NEC 502.10(A)(1), NEC 502.115(A)), commercial garage zone requirements (NEC 511.3(A), NEC 511.3(B)(3)), and swimming pool wiring rules (NEC 680.22(B), NEC, Section 680.23(A)(4), NEC, Section 680.26(B)).

Low Voltage, Alarms, Signaling Systems, and Communications (10 items) covers Class 2 and Class 3 remote-control circuits (NEC 725.136(A), NEC 725.136(G)), fire alarm wiring (NEC 760.41(B), NEC 760.43, NEC 760.49(A)), communications cable separation (NEC, Section 800.133(B)), coaxial cable (NEC, Section 820.93(A)), photovoltaic system disconnects and arc-fault protection (NEC 690.11, NEC 690.12(B)(1), NEC 690.7), and fiber optics.

Lighting and Signs (7 items) addresses fixture installation clearances (NEC Handbook, Section 410.10(C), NEC Handbook, Section 410.11), recessed fixture requirements (NEC 410.116(A)(2) and NEC 410.116(B)), sign branch circuits (NEC 600.5(A), NEC 600.5(C)(1)), sign grounding (NEC 600.7(A)(5), NEC 600.7(B)(7)), and luminaire wiring methods.

Safety (8 items) draws from OSHA 29 CFR 1926. Expect questions on PPE responsibility (OSHA 1926 CFR 29, §1926.28), emergency action plans (OSHA 1926 CFR 29, §1926.35(b), §1926.35(e)(3)), job site sanitation (OSHA 1926 CFR 29, §1926.51(a)(4)), first aid (OSHA 1926 CFR 29, §1926.50(d)(2)), and safety training (OSHA 1926 CFR 29, §1926.21(b)(3)).

Motors and Transformers (6 items) covers single motor conductor sizing at 125% (NEC 430.22(A)), multiple motor feeder sizing (NEC 430.24), overcurrent protection selection from NEC Table 430.52(C)(1), transformer overcurrent protection from NEC Table 450.3(B), and transformer installation requirements (NEC 450.21(A), NEC 450.21(B), NEC 450.9, NEC 450.14).

Worked Sample Questions

Question 1 — Grounding and Bonding

Two sets of 400 kcmil copper SE conductors feed a service. What is the minimum bonding jumper size?

• A. 1/0 AWG
• B. 2/0 AWG
• C. 3/0 AWG
• D. 4/0 AWG

Correct Answer: B — 2/0 AWG

Add the two sets together: 2 × 400 kcmil = 800 kcmil total copper. NEC Table 250.102(C)(1) places 800 kcmil in the "over 600 through 1,100 kcmil" copper range, which requires a 2/0 AWG copper bonding jumper. The trap here is forgetting to sum both sets before looking up the table — candidates who look up 400 kcmil alone land on the wrong row and select 1/0 AWG.

Question 2 — Conductors and Cables

What is the minimum copper conductor size for a 200A residential service using THHN at 75°C terminals?

• A. 2/0 AWG
• B. 3/0 AWG
• C. 250 kcmil
• D. 300 kcmil

Correct Answer: B — 3/0 AWG

NEC Table 310.4(1) / Table 310.16 shows that 3/0 AWG copper THHN is rated 200A at the 75°C column. Because the terminals are rated 75°C, you use the 75°C ampacity column regardless of the insulation's higher rating. Candidates who use the 90°C column or who confuse aluminum ampacities with copper will choose 250 kcmil — a common error.

Question 3 — Special Occupancies and Equipment

In hospital isolated power systems, line isolation monitors must alarm if leakage exceeds:

• A. 2 mA
• B. 3 mA
• C. 5 mA
• D. 10 mA

Correct Answer: C — 5 mA

NEC 517.160(B) states that the line isolation monitor shall be designed to provide a continuous indication and alarm when total hazard current reaches 5 mA. The lower values (2 mA, 3 mA) sound plausible as safety thresholds but do not match the code requirement. The 10 mA option is well above the permitted alarm point. This is a straight code recall question — know the number.

How to Read Your Score

The passing mark is 70% — 70 correct out of 100. If you take the full practice exam and score in the 50s or 60s, treat that as diagnostic information, not failure. Most candidates score below passing on their first attempt; the value of that attempt is identifying which of the 13 topic areas cost you the most points.

After each attempt, look at your results by topic. A score of 60% on Grounding and Bonding (10 items) costs you more than a 60% on General Electrical Knowledge (4 items) — weight your study time accordingly. Grounding and Bonding, Conductors and Cables, Special Occupancies, and Low Voltage each carry 10 items, so weak performance in any of those four topics has an outsized effect on your total.

Scoring 70–75% on a practice exam with a 707+ question pool does not mean you are ready — it means you are close. The real exam will include items you haven't seen. Aim for consistent 80%+ scores across multiple unique attempts before scheduling the licensing exam. The free exam is a good first temperature check; the full exam is where real preparation happens.

Where Candidates Lose Points

Grounding and Bonding is where the most points leak. Candidates confuse grounding electrode conductor sizing with equipment grounding conductor sizing — they come from different tables and follow different rules. Read the question carefully to identify which conductor is being asked about.

Conductors and Cables trips people who forget terminal temperature ratings. THHN is a 90°C insulation, but if the terminal is rated 75°C, you use the 75°C ampacity column. This mistake appears in both conductor selection and service entrance questions.

Motors and Transformers involves multi-step calculations. NEC 430.24 requires summing all motor full-load currents plus 25% of the largest motor — candidates who skip the 25% adder or pull from the wrong table (NEC Table 430.248 vs. NEC Table 430.250) get the wrong answer.

Special Occupancies questions often hinge on a specific voltage or milliamp threshold — like the 5 mA hospital alarm level — that has no obvious logic. These must be memorized from the code, not reasoned out.

Time management is a real issue. With 100 questions and 240 minutes, you have 2.4 minutes per question. Calculation-heavy sections like Services, Feeders, and Branch Circuits can easily consume 4–5 minutes per question if you're looking up tables under pressure. Practice working calculations without a spotter.

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