Scope: this covers Japan's Second-Class Electrician national examination for work on general-use electrical installations (一般用電気工作物). The written component is four-choice and may be taken on paper or by CBT, covering electrical theory, distribution and wiring design, equipment and materials, construction methods, inspection, wiring diagrams, and safety law. The practical component is a timed build from a given wiring diagram using materials provided at the test site and your own tools, judged for defects. Official materials state a written pass mark of 60 and a practical standard of no defects, but check the current official candidate guide for dates, fees, venues, exemptions, and other administrative details — and note that this is subject review, not a practical-exam simulation. Short answer: prepare for two linked but different assessments—a four-choice written test of electrical knowledge and diagram interpretation, and a practical build judged for defects. The 20 MCQs below are a preview that checks supporting knowledge only; they are not full syllabus coverage and are not a simulation of either the full written examination or the practical examination.
Scope, components, and what is assessed
The credential has a written knowledge gate and a separate practical build; study them differently. The Type 2 scope is work on general-use electrical installations (一般用電気工作物), not all electrical work.
The examination covers the knowledge and skills needed for safety of general-use electrical installations (一般用電気工作物) in Japan. The written test uses four-choice questions and can be taken on paper or by CBT; the official guide states that question format and difficulty are unchanged between those delivery modes. Its subject areas include basic electrical theory, distribution and wiring design, equipment, materials and tools, construction methods, inspection methods, wiring diagrams, and safety law. The practical test is open to those who pass the written test or hold an approved exemption. You use materials provided at the test site and your own tools to complete a problem given as a wiring diagram within the set time.
The practical examination is not a written quiz. Expect it to assess connections, wiring work, installation of equipment and wiring devices, use of materials and tools, attachment of cords and cabtyre cables, grounding work, measurement of current, voltage, power and resistance, inspection, and repair of fault locations. Official materials state that the written pass mark is 60 and the practical standard is that the work has no defects. Check administrative rules, exemptions, dates and fees against the current official candidate guide rather than inferring them from this preview.
Preparation priorities
Spend most time on recurring calculations, diagram behavior, instrument logic, and safety judgment.
First priority is calculation fluency: Ohm's law, series and parallel resistance, current division, power, energy, RMS values, and power factor. These ideas reappear in equipment, inspection and practical reasoning. Second priority is control and sequence diagrams: normally open and normally closed contacts, self-holding, stop circuits, overload contacts, and interlocks. Third is inspection and measurement: choosing the right instrument, preparing an isolated circuit, and interpreting a reading in context. Fourth is safety and protective judgment: isolation, hazard recognition, and coordinated selection of conductors and protective devices.
Use three passes. Pass one builds closed-book concept maps and symbol recognition. Pass two solves worked problems and traces diagrams aloud. Pass three uses mixed timed sets and an error log. Record why each error happened—unit conversion, formula choice, contact state, instrument choice, or unsafe assumption—so revision targets the cause rather than the topic label. For practical work, use supervised laboratory practice or paper-based connection schedules; do not treat reading about wiring as hands-on competence.
Circuit calculations with a worked scenario
Draw the equivalent circuit, compute total resistance, then apply Ohm's law and voltage or current division.
A 12 V source feeds a 6 Ω resistor in series with a parallel pair of 12 Ω and 24 Ω. The parallel equivalent is (12 × 24) ÷ (12 + 24) = 288 ÷ 36 = 8 Ω. Total resistance is 6 + 8 = 14 Ω. Source current is 12 ÷ 14 = 0.857 A. The parallel section voltage is 0.857 × 8 = 6.86 V. Branch currents are 6.86 ÷ 12 = 0.571 A and 6.86 ÷ 24 = 0.286 A, which add to 0.857 A. Check the series voltage: 0.857 × 6 = 5.14 V, and 5.14 + 6.86 = 12 V.
For parallel resistances, do not add them directly. For two resistors use the product over sum, or convert each to a conductance and add. For series circuits, current is common and voltage divides; for parallel circuits, voltage is common and current divides. Keep units visible: Ω, V, A, W, kWh. A useful check is to compute power from both V × I and I²R and see whether they agree.
AC values, power, and power factor
Separate peak from RMS, and separate apparent, active, and reactive power.
For a sine wave, RMS value is peak ÷ √2. A 100 V peak therefore corresponds to about 70.7 V RMS. Frequency is a separate property and does not change the amplitude relationship. In a simple resistive circuit, voltage and current are in phase, so power factor is 1. In a circuit with reactance, apparent power S = VI is larger than active power P = VI cos θ.
Worked example: a single-phase load takes 10 A at 200 V with power factor 0.6. Apparent power is 200 × 10 = 2,000 VA. Active power is 2,000 × 0.6 = 1,200 W. Reactive power is √(2,000² − 1,200²) = 1,600 var. If this load runs for four hours, energy is 1.2 kW × 4 h = 4.8 kWh. Read each question carefully: it may ask for active power in watts, apparent power in volt-amperes, or energy in kilowatt-hours. Power factor is not a measure of efficiency; it is the cosine of the phase angle between voltage and current.
Control and sequence diagrams
Trace the coil circuit from supply through every stop, overload, and interlock contact; parallel paths hold, series contacts stop.
In a self-holding circuit, a normally open start button is wired in parallel with a normally open auxiliary contact of the contactor. The stop button and any normally closed overload contact are in series with the coil. Pressing start energizes the coil, the auxiliary contact closes, and the coil remains energized after the start button is released. Pressing stop, or opening the overload contact, breaks the series path. The coil drops, the holding contact reopens, and a new start operation is required after the fault is reset.
For an interlock, place a normally closed auxiliary contact of contactor F in series with the coil of contactor R, and a normally closed auxiliary contact of R in series with the coil of F. Then F cannot be energized while R is held in, and vice versa. Trace the actual coil path rather than judging by the labels alone. Check whether each contact is drawn in its unoperated state, whether the holding contact is parallel to the start button, and whether the overload contact is in the coil circuit. A circuit that looks plausible can still fail if a normally closed contact is used where a normally open contact is required.
Inspection and measurement reasoning
Choose the instrument for the quantity, confirm isolation where required, and interpret the pattern rather than one number.
An insulation resistance tester is used for insulation resistance on an isolated circuit; a low-voltage multimeter is not a substitute. A clamp meter measures current through the magnetic field around a single conductor. If it is clamped around both line and neutral of a single-phase circuit, the opposing currents tend to cancel and the reading is near zero. A continuity test checks whether a low-resistance path exists. An earth tester measures earth electrode resistance. Select the instrument and range before connecting leads, prove the tester where appropriate, and isolate or discharge equipment according to the task and applicable procedure.
Scenario: three isolated final circuits read 0.2 MΩ, 20 MΩ, and 100 MΩ. The 0.2 MΩ result is the outlier and should be investigated while the circuit remains isolated. Look for moisture, damage, contamination, or a connection problem, then retest. Do not declare a pass or fail without the applicable criteria, and do not energize a suspect circuit to dry it out. A high insulation reading also does not prove that every terminal is correctly connected, so visual inspection and continuity checks remain necessary. In practical work, loose strands, wrong terminals, missing grounding, and damaged sheath are defects even if the circuit appears to function.
Safety and protective judgment
De-energize and verify before work; coordinate load, conductor, and protection; never improvise around a protective device.
A safe conceptual sequence is: plan the task, identify all sources, isolate, lock or tag as required, prove the voltage tester, verify de-energization, and prove the tester again (for example, on a known live source where available) before work; then restore in a controlled way. Insulated tools and appropriate personal protective equipment are used when the risk assessment requires them, especially for live-adjacent work, but gloves alone are not a substitute for isolation. Red flags include exposed live parts, water near equipment, burning smells, repeatedly blowing protective devices, and damaged cords. Stop and escalate rather than working around the hazard.
Protective judgment means coordinating the load, conductor capacity, protective-device rating, installation method, and earthing or bonding. Replacing a fuse or breaker with a larger rating to stop nuisance blowing is poor practice because the protective device may no longer protect the conductor. For an added load, check the existing circuit design before acceptance. Exact legal values and installation rules must come from the current applicable standards and official guidance; this guide teaches the reasoning principle, not a substitute rulebook.
Common errors to eliminate
Most lost marks come from predictable slips, not from lack of theory.
Theory errors include adding parallel resistances directly, using peak voltage where RMS is required, omitting power factor, and mixing mA with A or W with kW. Diagram errors include confusing normally open and normally closed contacts, omitting the overload contact, placing the holding contact in series with the start button instead of in parallel, and forgetting an interlock. Measurement errors include using a multimeter for insulation resistance, testing without confirming isolation, failing to prove the tester, and treating one odd reading as conclusive.
Practical errors include misreading the diagram, stripping or cutting conductors incorrectly, leaving loose strands, using the wrong terminal, omitting grounding, and rushing without a continuity check. Safety errors include assuming a circuit is dead because a switch is off, failing to lock or tag, using damaged tools, and relying on PPE instead of engineering controls. Build a short checklist for each domain and use it after every practice attempt. The checklist should force you to state the quantity being measured, the instrument selected, the expected result, and the action to take if the result is abnormal.
Integrated practice task and self-check
Use one open task that joins diagram reading, calculation, measurement choice, and defect reasoning.
Open-task practice: take a simple control diagram containing a start button, stop button, overload contact, contactor coil, holding contact, and indicator lamp, plus a final circuit with a stated load. Produce a terminal-to-terminal connection schedule. Calculate the branch current, total active power, and energy for a stated number of hours. Select conceptually appropriate instruments for continuity, insulation resistance, earth resistance, and current. List pre-energization checks and three likely defects. Write the safe isolation sequence you would expect before any work. If you have no supervised workshop, redraw the diagram and narrate the connections; do not attempt unsupervised wiring or live testing.
Self-check rubric, 20 points: calculations correct with units, 4; diagram logic including normally open, normally closed, self-holding and interlock, 4; instrument and isolation choices, 3; defect identification and safety red flags, 4; complete labeled connection schedule and sequence, 3; self-check catches inconsistencies, 2. A score below 16 means revisit the weakest domain before a timed rehearsal. A score of 16 to 18 means repeat the task with a different diagram. A score of 19 or 20 means move to mixed questions and supervised practical rehearsal. The multiple-choice preview is not a practical simulation and does not replace a defect-based build.
Practical study sequence
Build fluency in layers, then rehearse mixed and open tasks under realistic constraints.
A four-week conceptual plan: week 1, daily calculation practice and unit checks; week 2, ladder and sequence diagrams, including self-holding and interlocks; week 3, inspection, measurement selection, and safety judgment; week 4, mixed timed sets and the open task above. A 40-minute session can be split into 10 minutes of recall, 20 minutes of worked problems, and 10 minutes of error-log review. Do not memorize administrative dates, fees, or exemption details from a preview; use the current official candidate guide for those.
For the practical component, practise only under supervision with the materials and tools permitted in that setting. Use a material check when instructed, time checkpoints, a connection schedule, and a final defect checklist. If workshop access is unavailable, draw diagrams, write terminal schedules, and explain the operation of each contact; do not claim hands-on competence from paper practice. Finish preparation by taking the 20 questions timed, then explain every wrong answer and one right answer aloud to confirm that your reasoning, not just your memory, is correct.
References and further reading
Use these references to explore the concepts and check the latest information from the relevant organizations.