FREE Journeyman Electrician Study Guide 2026

This free journeyman electrician study guide walks through the core knowledge the licensing exam tests, organized around the National Electrical Code (NEC, NFPA 70) that the exam is built on.^[1]

It’s interactive, not a wall of text: every module has built-in checkpoint quizzes, flashcards, and practice questions, so you learn by doing — not just reading.

The journeyman exam is state-administered (often delivered by PSI or Prometric) and varies by jurisdiction, but it always rests on three pillars: electrical theory, electrical calculations, and NEC code lookup. We teach them in five study modules.

Read a module, test yourself at each checkpoint, then drill gaps with our free practice test and flashcards. This guide is a high-yield overview that maps the tested content — not a replacement for the Code book itself.

Journeyman Electrician Exam Snapshot

Because the exam is largely code-based and open-book, two skills decide your score: doing the standard calculations quickly, and navigating the NEC to the right article and table fast.^[1] Plan your study by where the questions cluster:

Topic proportions are approximate and based on common state journeyman content outlines (for example, the Texas TDLR/PSI outline); exact weights differ by jurisdiction and Code cycle.^[6]

Module 1 · Electrical Theory & Calculations

The math under everything else. You can’t size conductors, set overcurrent protection, or check a service without the theory behind it. This module covers Ohm’s law and power, series and parallel circuits, and voltage drop.

1.1 Ohm’s Law & Power

Everything starts with Ohm's law: E = I × R, where voltage (E) equals current (I) times resistance (R). Rearranged, I = E ÷ R and R = E ÷ I. Power in watts is P = E × I, and with Ohm’s law also P = I² × R or P = E² ÷ R.^[8]

AC adds two wrinkles the exam loves. For Single-phase power, multiply by Power factor: P = E × I × PF. For Three-phase, also multiply by the square root of three: P = 1.732 × E × I × PF. Memorize that 1.732 — it shows up on nearly every three-phase question.

1.2 Series & Parallel Circuits

In a Series circuit there is one path: the current is the same everywhere, and resistances add (R = R₁ + R₂ + R₃). Open it anywhere and everything goes dark. In a Parallel circuit there are multiple paths: the voltage is the same across every branch, and the total resistance is less than the smallest branch.

For parallel resistances, 1/R = 1/R₁ + 1/R₂ + 1/R₃. A handy shortcut: two equal resistors in parallel give exactly half the value (two 20-ohm resistors in parallel = 10 ohms). Building branch circuits are wired in parallel so each device gets full voltage and one failure doesn’t kill the rest.

1.3 Voltage Drop

Voltage drop is the voltage lost to a conductor’s resistance as current flows. It grows with longer runs, smaller wire, and more current. The NEC recommends keeping drop to 3% on a branch circuit or feeder and 5% total so motors and equipment run properly.^[1]

The single-phase formula is VD = (2 × K × I × L) ÷ CM, where K ≈ 12.9 for copper (21.2 for aluminum), I is the current, L is the one-way length in feet, and CM is the conductor’s circular mils. For three-phase, replace the 2 with 1.732. Excess drop dims lights, slows motors, and wastes energy as heat.

Module 2 · Services, Grounding & Bonding

Where the building connects to the utility — and how it’s made safe. This module covers services and service conductors (Article 230) and the most-confused topic on the exam, grounding and bonding (Article 250).

2.1 Services & Service Conductors

The Service is the conductors and equipment that bring power from the utility into the building. A one-family dwelling service must be rated at least 100 amperes, three-wire.Service-entrance conductors run from the meter to the service disconnect and must have an ampacity at least equal to the calculated load.^[1]

A special allowance helps here: for 120/240-volt single-phase dwelling services and main feeders, the NEC permits conductors sized at 83% of the service rating (the dwelling services/feeders table), so a 200-amp dwelling service can use 2/0 copper instead of the larger size the general ampacity table would demand.

2.2 Grounding & Bonding

The exam constantly tests the difference. Grounding connects the system to the Grounding electrode (rod, pipe, plate, or concrete-encased “Ufer”) through the Grounding electrode conductor to stabilize voltage and dissipate surges. Bonding joins all metal together so it’s at the same potential, creating the low-impedance path that lets fault current trip the breaker.^[2]

Two sizing tables anchor this topic. The Grounding electrode conductor is sized from Table 250.66 — but capped at 6 AWG copper to a rod and 4 AWG copper to a concrete-encased electrode, no matter how big the service is. The Equipment grounding conductor is sized from Table 250.122 by the breaker rating. At the service, the Main bonding jumper ties the grounded (neutral) bus to the equipment ground; on a Separately derived system, the System bonding jumper does the same job.

Module 3 · Feeders & Load Calculations

How you turn a building’s loads into the right conductor and overcurrent sizes. This module covers load calculations (Article 220) and feeders (Article 215).

3.1 Load Calculations (Article 220)

For a dwelling, the general lighting and receptacle load is figured at 3 volt-amperes per square foot of habitable area. You add the two small-appliance circuits and the laundry circuit (1,500 VA each), then apply demand factors: the first 3,000 VA at 100%, 3,001–120,000 VA at 35%, and the remainder at 25%.^[1]

Continuous loads (running 3 hours or more) are sized at 125%. Specific loads have their own demand tables — ranges (220.55), dryers (220.54), and others — that reflect the fact that not everything runs at full load at once.

3.2 Feeders (Article 215)

A Feeder runs between the service equipment and the final branch-circuit overcurrent device. Its conductors must have an ampacity (before adjustment) of at least the noncontinuous load plus 125% of the continuous load, and never less than the calculated load it carries.^[1]

Fixed electric space heating is treated as a Continuous load, so it gets the 125% factor. When a feeder supplies subpanels, its ampacity must cover the total calculated load of everything downstream.

Module 4 · Wiring Methods, Conductors & Fill

The biggest single area of the exam. This is the day-to-day of the trade: choosing a wiring method, sizing and protecting conductors, and getting conduit and box fill right.

4.1 Wiring Methods & Conductors

Know the common raceways and cables by their articles. EMT (Article 358) is thin-wall steel tubing — supported within 3 feet of every box and every 10 feet, with no more than 360 degrees of bends between pull points, and not permitted where subject to severe physical damage.

Type NM cable (Article 334, “Romex”) is for dry locations and dwellings, secured within 12 inches of a box and every 4.5 feet. Rigid metal conduit (Article 344) is the heavy-duty choice allowed almost anywhere.^[1]

Ampacity (Table 310.16) is the current a conductor can carry continuously — but the Small-conductor rule (240.4(D)) caps the breaker regardless: 14 AWG → 15 A, 12 AWG → 20 A, 10 AWG → 30 A. The Equipment grounding conductor runs with the circuit to provide the fault path, and Article 300 holds the general rules (securing, protection from damage) for all wiring methods.

4.2 Conduit & Box Fill

Conduit fill (Chapter 9, Table 1) limits how full a raceway can be: 53% for one conductor, 31% for exactly two, and 40% for three or more. The two- conductor case is the most restrictive on purpose — a tight pair can jam and damage insulation during the pull.^[1]

Box fill (314.16) makes sure a box is big enough. Each conductor counts as one; all grounding conductors together count as one; all cable clamps together count as one; and each device on a yoke counts as two— all based on the largest conductor involved. Multiply the total count by that conductor’s volume allowance.

Module 5 · Overcurrent, GFCI/AFCI & Safety

Protection and people. This module covers overcurrent protection (Article 240), GFCI/AFCI and receptacle placement (210.8, 210.12, 210.52), and electrical safety and working space.

5.1 Overcurrent Protection

An Overcurrent device (fuse or breaker) exists to protect the conductor from overheating. It must be readily accessible — the operating handle no more than 6 ft 7 in above the floor (240.24) — and not located over steps or in bathrooms or clothes closets.^[1]

Two big rules: the Small-conductor rule (240.4(D)) caps protection on small wires, and a Tap conductor is allowed under the 10-foot and 25-foot tap rules (240.21) to connect a smaller conductor to a larger circuit under specific conditions (the 25-ft tap must be at least one-third the feeder OCPD rating).

5.2 GFCI, AFCI & Receptacles

Don’t mix these up. A GFCI (210.8) protects people from shock by sensing tiny leakage to ground (≈4–6 mA) — required in kitchens, bathrooms, garages, basements, laundry, and outdoors. An AFCI (210.12) protects against fire by detecting arcing faults — required in dwelling living areas like bedrooms.^[4]

Receptacle spacing (210.52) follows the 6-foot rule: no point along a wall line is more than 6 feet from a receptacle, so receptacles sit no more than 12 feet apart, and any wall 2 feet or wider gets one. In kitchens, countertop receptacles are placed so no point is more than 24 inches from one, and any counter 12 inches or wider needs a receptacle. Replacing a receptacle where GFCI is now required triggers GFCI protection.

5.3 Safety & Working Space

Working space (110.26) keeps electricians safe at the panel: for systems up to 150 volts to ground, at least 3 feet deep (Condition 1), 30 inches wide (or the equipment width), and 6½ feet of headroom, with doors able to open at least 90 degrees. The space must stay clear — no storage.^[1]

Beyond the Code, OSHA governs job-site safety. The core rule is to treat every conductor as energized until it’s tested dead, and to use Lockout/tagout (OSHA 1910.147): de-energize, lock, tag, and verify before servicing.^[5] Wear the right PPE and respect minimum approach distances to energized parts.

How to Use This Journeyman Electrician Study Guide

This guide is built to be worked, not just read. The most efficient path to a pass:

• Master the calculations. Ohm’s law, power, voltage drop, conduit and box fill, and load calcs show up everywhere — drill them until they’re automatic.
• Learn to navigate the Code, not memorize it. The exam is open-book; speed at finding the right article and table is what wins.
• Check off as you go. Use the Study Guide Contents to mark each section done; it raises your exam-readiness score.
• Take every checkpoint. The end-of-module quizzes show you exactly which topics need another pass.
• Drill the weak area. Send it into the flashcards and a practice test until the score climbs.
• Confirm your Code edition. Study from the NEC edition your state has adopted (2023, 2020, or 2017) — article and table numbers can shift between editions.

Journeyman Electrician Glossary

The high-yield electrical and NEC terms in one place — hover any dotted term in the guide, or flip the whole deck here as a self-grading flashcard set.

AFCI

Arc-Fault Circuit Interrupter — detects dangerous arcing faults to prevent fire, required in dwelling living areas (210.12).

Ampacity

The maximum current a conductor can carry continuously without exceeding its temperature rating (Table 310.16).

AWG

American Wire Gauge — the sizing system for conductors; a smaller AWG number means a larger conductor.

Bonding

Joining metal parts together so they are at the same potential, creating the low-impedance fault path that trips the breaker.

Box fill

The required minimum box volume based on the conductors, clamps, fittings, and devices inside it (314.16).

Branch circuit

The conductors between the final overcurrent device and the outlets it serves (Article 210).

Conductor

A wire or other material that carries current; sized by AWG or kcmil and rated for an insulation temperature.

Conduit fill

The maximum percent of a raceway's cross-section conductors may occupy: 53% for one, 31% for two, 40% for three or more (Chapter 9, Table 1).

Continuous load

A load expected to operate for three hours or more; sized at 125% for conductors and overcurrent devices.

Current

The flow of electric charge, measured in amperes (I or A); the same in every part of a series circuit.

EMT

Electrical Metallic Tubing — a thin-wall steel raceway (Article 358); supported within 3 ft of boxes and every 10 ft.

Equipment grounding conductor

The conductor (EGC) that bonds non-current-carrying metal back to the source, providing the fault-current path; sized by Table 250.122.

Feeder

Conductors between the service equipment and the final branch-circuit overcurrent device (Article 215).

GFCI

Ground-Fault Circuit Interrupter — trips on small current leakage to ground (≈4–6 mA) to protect people from shock (210.8).

Grounded conductor

The conductor intentionally connected to ground, usually the neutral; not the same as the equipment grounding conductor.

Grounding

Connecting the electrical system to the earth through a grounding electrode conductor and electrode (Article 250).

Grounding electrode

The conducting object — ground rod, water pipe, concrete-encased (Ufer) electrode, or plate — that makes earth contact.

Grounding electrode conductor

The conductor (GEC) connecting the grounded system or equipment to the grounding electrode; sized by Table 250.66.

Lockout/tagout

The OSHA procedure (1910.147) for de-energizing, locking, tagging, and verifying equipment safe before servicing it.

Main bonding jumper

The connection at the service that bonds the grounded (neutral) conductor to the equipment ground and enclosure.

NEC

The National Electrical Code (NFPA 70) — the model code, updated every three years, that journeyman exams are based on.

Ohm's law

The rule that voltage equals current times resistance (E = I × R); rearranged, it gives current or resistance from the other two values.

Overcurrent device

A fuse or circuit breaker that opens the circuit when current would overheat the conductor (Article 240).

Parallel circuit

A circuit with multiple paths; voltage is the same across every branch and total resistance is less than the smallest branch.

Power factor

The ratio of real power (watts) to apparent power (volt-amperes) in an AC circuit; 1.0 (unity) means all the power does useful work.

Raceway

An enclosed channel — conduit or tubing — designed to hold conductors.

Resistance

Opposition to current flow, measured in ohms (Ω); resistances add in series and combine reciprocally in parallel.

Rigid metal conduit

RMC — heavy-wall threaded steel conduit (Article 344) permitted in nearly all locations, including severe physical damage.

Separately derived system

A system whose power is derived from a source (like a transformer or generator) with no direct electrical connection to the supply conductors.

Series circuit

A circuit with one current path; current is the same everywhere and resistances add up.

Service

The conductors and equipment that deliver electricity from the utility to a building's wiring (Article 230).

Service-entrance conductors

The conductors from the service point or meter to the service disconnect; a one-family dwelling service must be at least 100 A.

Single-phase

An AC supply with one alternating voltage (commonly 120/240 V in dwellings); power = E × I × power factor.

Small-conductor rule

240.4(D): caps overcurrent protection at 15 A for 14 AWG, 20 A for 12 AWG, and 30 A for 10 AWG copper, regardless of ampacity.

System bonding jumper

The equivalent of the main bonding jumper for a separately derived system, such as a transformer secondary.

Tap conductor

A conductor with overcurrent protection ahead of it larger than its ampacity normally allows; permitted under the 10-ft and 25-ft tap rules (240.21).

Three-phase

An AC supply with three voltages 120° apart, used for larger loads; power = 1.732 × E × I × power factor.

Type NM cable

Nonmetallic-sheathed cable (Romex), used mainly in dry locations and dwellings (Article 334); secured within 12 in of boxes and every 4.5 ft.

Voltage

Electrical pressure or potential difference, measured in volts (E or V) — what pushes current through a circuit.

Voltage drop

The loss of voltage along a conductor due to its resistance; the NEC recommends ≤3% on a branch or feeder and ≤5% total.

Working space

The clear space required in front of equipment so it can be serviced safely (110.26) — for ≤150 V, at least 3 ft deep, 30 in wide, 6½ ft high.

Journeyman Electrician Study Guide FAQ

References

1. 1.National Fire Protection Association. “NFPA 70, National Electrical Code (NEC).” nfpa.org. ↑
2. 2.National Fire Protection Association. “Grounding vs. Bonding (NEC Article 250).” nfpa.org. ↑
3. 3.Occupational Safety and Health Administration. “Electrical — Safety Standards.” osha.gov. ↑
4. 4.Occupational Safety and Health Administration. “Ground-Fault Protection on Construction Sites (1926.404).” osha.gov. ↑
5. 5.Occupational Safety and Health Administration. “The Control of Hazardous Energy (Lockout/Tagout), 1910.147.” osha.gov. ↑
6. 6.Texas Department of Licensing and Regulation. “Electricians — Licensing & Examination.” tdlr.texas.gov. ↑
7. 7.PSI Exams. “Electrical Examination Candidate Information.” psiexams.com. ↑
8. 8.U.S. Department of Energy. “Determining Electric Motor Load and Efficiency.” energy.gov. ↑
9. 101.National Institute of Standards and Technology. “The Ohm and Ohm's Law.” nist.gov, accessed 20 June 2026. ↑

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