The most-missed topics on the electrician exam
Most candidates who fail knew enough to pass. They lost the exam in a handful of predictable places. Here is where the points actually go, ranked, with the trap and the fix for each.
Last reviewed June 2026
The short version
Calculations fail more candidates than anything else, led by conduit fill, box fill, motors, and load calculations. After that come grounding versus bonding, voltage drop, and the speed of finding rules in the book. None of it is hard math. It is setup under time pressure and a small set of repeatable traps.
What the pass-rate data shows
Texas splits the TDLR Journeyman exam into two separately-scored parts. The most recent published pass rates were 27.52% overall, 24.46% on the NEC Knowledge part, and 20.56% on the Calculations part. The Calculations part is the lowest, and since the split a strong code score no longer rescues a weak math score.
California weights its General Electrician exam toward Installation at 66 percent and calculations at 22 percent of the outline. Its most recent published pass rates were 52.95% for first-time candidates and 38.02% for repeat candidates. The drop on retake is mostly about prep strategy, not ability.
The ranking
1. Calculations as a whole
Why it costs points: In Texas the Calculations part is now timed and scored separately, and the most recent published pass rate on it was 20.56%, below the 24.46% on the NEC Knowledge part. A strong code score no longer carries a weak math score.
The trap: Treating calculations as one big scary block instead of a handful of repeatable patterns. Candidates freeze on multi-step problems because they never built a fixed setup.
The fix: Use one five-step setup on every problem: name it, pick the formula or table, plug values, run the math, check the rule. Drill one calc type at a time until the setup is automatic.
2. Conduit fill
Why it costs points: Conduit fill shows up across every exam and looks simple, which is exactly why it leaks points. It is a five-step count, and one wrong percentage moves the whole answer.
The trap: Reaching for 40 percent on every problem. The limit is set by the conductor count: one wire 53 percent, two wires 31 percent, three or more 40 percent.
The fix: Count the conductors first, then pick the percentage. Pull wire areas from Chapter 9 Table 5, total them, and compare against the raceway in Table 4.
3. Box fill
Why it costs points: Box fill is pure counting tied to Article 314.16, and the count rules are easy to misremember under pressure.
The trap: Missing the device-yoke count of two, or counting each ground separately. A device or yoke counts as two, and all equipment grounding conductors together count as one.
The fix: Count conductors, clamps as one, supports as one, devices as two, and grounds as one, then multiply each by the volume for the largest conductor present from Table 314.16(B).
4. Motors
Why it costs points: Motor problems chain several steps, and the exam writes them to punish one specific confusion.
The trap: Mixing FLC with FLA. Full-load current from the Article 430 tables sizes the conductors and protection. Nameplate FLA sizes only the overload.
The fix: Always read FLC from the table first, size conductors at 125 percent under 430.22, then handle protection and overload. Never plug the nameplate value into a conductor calc.
5. Grounding versus bonding
Why it costs points: Article 250 is large, and the exam deliberately blurs grounding and bonding to see if you know which conductor and table apply.
The trap: Confusing the grounding electrode conductor with the equipment grounding conductor. The GEC sizes from Table 250.66 by service conductor. The EGC sizes from Table 250.122 by the overcurrent device.
The fix: Anchor each conductor to its table and its input. Remember that upsizing phase conductors for voltage drop also upsizes the equipment grounding conductor under 250.122(B).
6. Voltage drop
Why it costs points: Voltage drop is a high-frequency calculation, and the formula has two easy places to slip.
The trap: Forgetting the factor of 2 for the single-phase round trip, or using the overcurrent rating instead of the operating current.
The fix: Single-phase uses 2 for the round trip, three-phase uses 1.732. Use the operating current, not the breaker rating, and pull circular mils from Chapter 9 Table 8.
7. Code-lookup speed
Why it costs points: Every open-book and provided-reference exam is a time race. Most candidates who fail knew the material but ran out of clock.
The trap: Hunting through the index or the whole book instead of jumping to the article neighborhood, and burning minutes on one stubborn question.
The fix: Learn where rules live: grounding 250, conductors 310, boxes 314, motors 430, fill in Chapter 9. Past about 90 seconds on a lookup, mark it and move on.
8. Load calculations and demand factors
Why it costs points: Dwelling and commercial load calculations stack several rules, and the demand factors are where candidates lose track.
The trap: Adding connected load without applying the Article 220 demand factors, or applying the wrong factor to ranges, dryers, or general lighting.
The fix: Work the calculation in order and apply the demand factors from 220.42, 220.55, and 220.54 at the right step. Continuous loads still carry the 125 percent rule.
How to use this list
Do not study all eight at once. Run the free diagnostic, find your bottom two, and drill those first. The candidates who pass on a retake read their score report, attack the weak two, and stop re-studying what they already know.
Common questions
What is the hardest part of the electrician exam?
Calculations. On the Texas TDLR Journeyman exam the Calculations part is scored on its own, and the most recent published pass rate on it was 20.56 percent, the lower of the two parts. The math itself is not hard. Setup under time pressure and slow code lookups are what cost candidates the points.
What topics fail the most electrician exam candidates?
Calculations lead, especially conduit fill, box fill, motors, and load calculations. After that come grounding versus bonding, voltage drop, and code-lookup speed. Each one has a small number of repeatable traps that account for most of the lost points.
Why do so many electricians fail the licensing exam?
Most candidates who fail knew enough to pass. They ran out of time, froze on a multi-step calculation, or used the wrong table. The skills that decide the exam are finding rules fast under test-center reference rules and running calculations with a clean, repeatable setup.
Sources
- TDLR Electrician Exam Information
- TDLR Journeyman Electrician application
- PSI / TDLR Electrician Candidate Information Bulletin
- TDLR FY2025 Electrician Exam Statistics
- DIR Electrician Certification Program
- Electrical Certification Candidate Information Bulletin
- DIR 2022 Electrical Exam Statistics
NEC article and table numbers are facts and freely citable. We paraphrase the code and never reproduce its text. JourneymanIQ is not affiliated with NFPA, TDLR, PSI, or the California DIR.
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