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Oklahoma Limited Electrical Contractor Practice Exam

What This Practice Exam Covers

The Oklahoma Limited Electrical Contractor exam is 100 questions with a 240-minute time limit. You need a 70% — 70 correct answers — to pass. The exam spans 13 topic areas drawn from NEC requirements, electrical theory, and job-site safety rules enforced in Oklahoma.

This practice exam gives you two options:

Free practice exam: 10 questions per attempt, drawn from a limited pool. You can retake it as many times as you want. It is a genuine preview of the question style and difficulty — useful for getting your bearings before committing to deeper preparation.

Full practice exam (paid): 100 questions, 240-minute time limit — a mirror of the real exam in length and structure. Questions are pulled from a pool of 500+ items, so every attempt gives you a different set. No two attempts are identical, which means repeated full runs build real coverage rather than question memorization.

What You'll Be Tested On

General Knowledge — 4 items
This section covers permits and inspections, preservation of structural integrity, and needs analysis and estimates. Expect questions on when permits are required, what triggers an inspection, and how to assess job scope before starting work. Four items sounds light, but a miss here costs the same as anywhere else.

General Electrical Knowledge — 10 items
This is one of the heavier calculation sections. You must be able to solve for voltage, current, and resistance in series, parallel, and combination circuits. Power calculations appear in two forms: power used in a circuit (watts and kilowatts) and power lost as heat in any circuit (I²R losses). The section also covers fundamental AC theory — impedance, reactance, phase relationships — and three-phase AC theory, where formulas use the 1.73 factor for √3. Cost of power (kilowatt-hours × rate) rounds out the section. Bring a calculator and know your formulas cold.

Electrical Installation Requirements — 10 items
Approved methods of installation for standard-voltage equipment and for equipment in excess of 600 volts are both tested. Questions probe conductor separation requirements, allowable wiring methods, and what the NEC permits in shared enclosures at different voltage levels.

Services, Feeders, and Branch Circuits — 10 items
Six subtopics at 10 items makes this one of the most concentrated sections. Services covers point-of-attachment heights and clearances. Voltage drop calculations appear for both branch circuits and feeders — know the formula and the NEC thresholds. Services in excess of 600 volts, feeder sizing, outside branch circuits and feeders, and branch circuit ratings all appear. Expect multi-step sizing problems.

Overcurrent Protection — 9 items
All 9 items fall under NEC overcurrent protection requirements. Questions test standard fuse and breaker ratings, next-standard-size rules, and the specific percentage-based limits for motor and transformer protection. Misreading a table here is the most common mistake.

Grounding and Bonding — 10 items
Three subtopics: general requirements, grounding electrode conductor sizing, and equipment grounding conductor sizing. Table lookups are required for both conductor sizes. Know the difference between a grounding electrode conductor and an equipment grounding conductor — the NEC treats them under separate tables and the exam tests exactly that distinction.

Conductors and Cables — 8 items
Six subtopics: underground conductors and cables (burial depths), vertical installations (support intervals), selecting conductors (ampacity and correction factors), armored cable Type AC, metal-clad cable Type MC, and nonmetallic-sheathed cable Types NM/NMC/NMS. Expect questions on where each cable type is and is not permitted.

Raceways and Boxes — 10 items
Covers general raceway requirements, box fill calculations, pull box sizing, conduit fittings, Type RMC (Rigid Metal Conduit), and Type EMT (Electrical Metallic Tubing). Box fill is a frequent calculation item — know how to count conductors, fittings, and devices correctly.

Special Occupancies and Equipment — 7 items
Class I, II, and III hazardous location wiring, commercial garages and fuel dispensing facilities, bulk storage plants and spray areas, general special occupancies, health facilities and places of assembly, and mobile home/RV parks are all in scope. These questions are detail-heavy and punish guessing.

Low Voltage, Alarms, Signaling Systems, and Communications — 6 items
Remote control and signaling circuits, communication circuits, equipment operating at 50 volts or less, fiber optics, photovoltaics, and remote controls. PV system requirements have grown in exam weight — know the NEC rules for DC circuits and disconnecting means.

Lighting and Signs — 4 items
Fixture installation, grounding, wiring, fluorescent fixtures, construction requirements, and recessed fixtures. Recessed fixture clearance from insulation and the rules for thermal protection are frequent targets.

Safety — 10 items
Job-site sanitation, PPE responsibility, excavation safety, emergency action plans, safety training requirements, and ventilation. These items are OSHA-grounded. Ten items makes this section as heavily weighted as Services or Grounding — do not treat it as an afterthought.

Motors and Transformers — 2 items
Motors in dwellings, motor branch circuits in industrial and commercial locations, feeder transformers, and transformer use. Only 2 items, but they test specific percentage rules for overcurrent protection of motors and transformers.

Worked Sample Questions

Question 1 — General Electrical Knowledge

What is the formula used to calculate current (amperes) in a three-phase circuit when kilowatts are known?

• A. I = KW × 1000 / (E × PF)
• B. I = KW × 1000 / (E × PF × 1.73)
• C. I = KW × 1000 / (E × PF × 2)
• D. I = KW × 1000 / E

Correct Answer: B

Three-phase power involves three conductors with voltages 120° apart. The relationship between line voltage and phase voltage introduces a √3 factor, which is approximately 1.73. Omitting it (Option A) gives you the single-phase formula. Using 2 (Option C) has no electrical basis. Option D drops both the power factor and the three-phase factor entirely. The complete formula — KW × 1000 divided by (E × PF × 1.73) — accounts for all three variables. Source: Ugly's Electrical References, Electrical Formulas, Book Pages 15–23.

Question 2 — Electrical Installation Requirements

Conductors of circuits rated over 1000 volts AC shall NOT occupy the same equipment wiring enclosure, cable, or raceway with conductors rated 1000 volts or less UNLESS specifically permitted. Which of the following is a permitted exception?

• A. When both circuits serve the same panel
• B. When excitation, control, relay, and ammeter conductors are used in connection with an individual motor or starter
• C. When the conductors are all copper and rated for wet locations
• D. When the raceway is rigid metal conduit

Correct Answer: B

The NEC creates a hard separation rule for different voltage classes, but it carves out a specific functional exception: excitation, control, relay, and ammeter conductors tied to an individual motor or starter may share the enclosure with the motor-circuit conductors. Options A, C, and D describe conditions that do not appear in the NEC as recognized exceptions to this rule. Source: NEC 305.4.

Question 3 — Services, Feeders, and Branch Circuits

What is the minimum point of attachment height above finished grade for overhead service conductors to a building?

• A. 2.5 m (8 ft)
• B. 3.0 m (10 ft)
• C. 3.7 m (12 ft)
• D. 4.5 m (15 ft)

Correct Answer: B

The NEC sets 3.0 m (10 ft) above finished grade as the absolute minimum attachment height. This is a floor, not a typical value — clearance rules in 230.9 and 230.24 may require more depending on the situation, but nothing less than 10 ft is ever acceptable. Candidates who confuse this figure with conductor clearance heights above ground (which are higher) choose Option C or D. Source: NEC 230.26.

How to Read Your Score

Passing requires 70 correct out of 100. On your first full practice attempt, your score is a diagnostic — it tells you where you stand right now, not where you will be on exam day.

A score in the 50s on a first attempt is not cause for alarm; it is useful data. A score of 65–68% is closer to passing but is not close enough — candidates who score in that band on practice exams frequently fall short on the real exam because test-day pressure and unfamiliar question phrasing cost a few extra points.

Use the topic-by-topic breakdown after every attempt. If you scored 4 out of 10 on Grounding and Bonding, that section needs focused table work before your next attempt. If you scored 8 out of 10 on Safety but 5 out of 9 on Overcurrent Protection, do not study Safety again this week. The breakdown tells you exactly where the points are being lost.

A comfortable target before scheduling the real exam is consistent scoring in the high 70s or above across multiple full practice attempts — with no single topic area in freefall.

Where Candidates Lose Points

Calculation errors in General Electrical Knowledge. Candidates drop the 1.73 factor on three-phase problems, or use the wrong power formula (confusing apparent power with real power). These are not trick questions — they reward candidates who practiced the formulas under time pressure.

Wrong table in Grounding and Bonding. The NEC has separate tables for grounding electrode conductors and equipment grounding conductors. Pulling from the wrong one produces a plausible but incorrect answer. Know which table applies to which conductor type before exam day.

Box fill miscounts in Raceways and Boxes. Candidates count conductors but forget to add the deductions for fittings and devices, or they miscount cable clamps. Box fill is a multi-step problem where skipping one step produces a wrong answer that still looks reasonable.

Misread clearances in Services, Feeders, and Branch Circuits. Point-of-attachment height, conductor clearances above grade, and clearances over rooftops are three different values. Conflating them is a consistent source of missed items.

Treating Safety as filler. With 10 exam items, Safety carries the same weight as Grounding and Bonding or Raceways and Boxes. Candidates who skip OSHA-related content on excavation safety, PPE responsibility, and emergency action plans are giving up points unnecessarily.

Running out of time. 240 minutes for 100 questions is 2 minutes 24 seconds per question. Multi-step calculations in Services and General Electrical Knowledge can eat 4–5 minutes if you are not practiced. Use full timed attempts on the practice exam so pacing is not a surprise on test day.

Exam Quick Facts