NATE Exam Prep: Core Practice Questions and 4-Week Study Plan
Use this NATE exam prep set to review Core foundations with 25 original, unofficial questions, two worked examples and a four-week plan—not a full-length exam or complete specialty guide. Pick an answer before you read its explanation; the safety and circuit scenarios are study exercises, not field-work instructions.
NATE Core practice questions
Question 1 · Safety
Three authorized technicians are doing routine maintenance on the same rooftop unit under OSHA's general-industry lockout rule. They use a group lockout box with personal locks. Who attaches a personal lock?
- A. Each authorized employee working on the equipment
- B. Only the lead technician
- C. The building owner
- D. Nobody — the lock on the group box covers everyone
Show answer and explanation for question 1
Answer: A. Each authorized employee working on the equipment.
OSHA requires each authorized employee to attach their own personal device to the group lockout mechanism when beginning work. In this lockout setup, that means a personal lock for each technician. One lead tech's lock (B) or a single box lock (D) does not replace each worker's personal protection. Being the building owner (C) does not make someone the authorized employee doing the work. A tag is a warning device, not the physical restraint provided by a lock. Source: 29 CFR 1910.147(f)(3)(ii)(D), (c)(7)(ii)(A).
Question 2 · Safety
On the safety data sheet (SDS) for a refrigerant you carry, which section lists exposure limits and the personal protective equipment to wear?
- A. Section 2 — Hazard(s) identification
- B. Section 8 — Exposure controls/personal protection
- C. Section 4 — First-aid measures
- D. Section 14 — Transport information
Show answer and explanation for question 2
Answer: B. Section 8 — Exposure controls/personal protection.
OSHA's SDS format places exposure limits, engineering controls and personal protective equipment (PPE) in Section 8. Section 2 tells you what the hazards are, Section 4 what to do after an exposure, and Section 14 how the product ships. Source: 29 CFR 1910.1200 Appendix D, Sections 2, 4, 8 and 14.
Question 3 · Safety
On an ordinary HVAC construction job, you need a ladder in a spot where you or the ladder could touch exposed energized electrical equipment. Which ladder meets OSHA's side-rail requirement?
- A. An aluminum extension ladder
- B. An aluminum ladder with rubber feet
- C. A steel stepladder
- D. A ladder with nonconductive side rails
Show answer and explanation for question 3
Answer: D. A ladder with nonconductive side rails.
OSHA requires nonconductive side rails where the employee or the ladder could contact exposed energized equipment. Rubber feet (B) don't change the rails, and the rails are what you'd touch or what would touch a live part. Aluminum and steel (A, C) conduct. A nonconductive ladder is not permission to touch energized equipment. Source: 29 CFR 1926.1053(b)(12).
Question 4 · Safety
An oxygen cylinder and an acetylene cylinder are in a designated, well-ventilated construction-site storage area, not connected for use. There's no fire-rated barrier between them. What is OSHA's minimum separation distance?
- A. 5 feet
- B. 10 feet
- C. 15 feet
- D. 20 feet
Show answer and explanation for question 4
Answer: D. 20 feet.
Oxygen cylinders in storage must be kept at least 20 feet from fuel-gas cylinders or combustible materials (especially oil or grease). The alternative is a noncombustible barrier at least 5 feet high with at least a half-hour fire-resistance rating. The 5-foot figure (A) is the barrier height, not a distance. Ten and fifteen feet (B, C) are below the required separation when there is no qualifying barrier. Source: 29 CFR 1926.350(a)(10); the general-industry rule matches at 29 CFR 1910.253(b)(4)(iii).
Question 5 · Safety
You bring a nitrogen cylinder to a job to purge lines while brazing. Under OSHA's construction gas welding and cutting rule, how must a compressed gas cylinder be kept?
- A. Secured upright at all times, except, if necessary, briefly while it's actually being hoisted or carried
- B. Lying flat so it can't tip over
- C. Upright, but it only needs to be secured overnight
- D. In any position, as long as the valve cap is on
Show answer and explanation for question 5
Answer: A. Secured upright at all times, except, if necessary, briefly while it's actually being hoisted or carried.
OSHA requires compressed gas cylinders to be secured upright at all times. The stated exception is, if necessary, short periods while the cylinder is actually being hoisted or carried. Lying it flat (B), securing it only overnight (C), or relying on the cap (D) doesn't meet that rule. Source: 29 CFR 1926.350(a)(9).
Question 6 · Tools
A spec sheet lists a 5/8-inch line connection. What is that in millimeters, to one decimal place?
- A. 14.2 mm
- B. 15.9 mm
- C. 16.5 mm
- D. 17.4 mm
Show answer and explanation for question 6
Answer: B. 15.9 mm.
One inch is exactly 25.4 mm. 5/8 = 0.625, and 0.625 × 25.4 = 15.875, which rounds to 15.9 mm. Source: NIST, SI Units – Length.
Question 7 · Tools
Your tape measure reads 2 ft 7 3/8 in. What is that in decimal inches?
- A. 24.375 in
- B. 31.375 in
- C. 31.83 in
- D. 32.375 in
Show answer and explanation for question 7
Answer: B. 31.375 in.
2 ft = 24 in. 24 + 7 = 31 in. 3/8 = 0.375. Total: 31.375 in. C misreads 3/8 as 0.83, D adds an extra inch, and A drops the 7 inches. Worked arithmetic.
Question 8 · Basic Construction
A floor plan is drawn at 1/4 inch = 1 foot. A room measures 3 inches by 4 inches on the drawing. What is its actual floor area?
- A. 12 sq ft
- B. 48 sq ft
- C. 192 sq ft
- D. 768 sq ft
Show answer and explanation for question 8
Answer: C. 192 sq ft.
At 1/4 inch = 1 foot, every inch on the drawing is 4 feet. The room is 3 × 4 = 12 ft by 4 × 4 = 16 ft, so its area is 12 × 16 = 192 sq ft. A multiplies the drawing inches without scaling. B scales only one side. D uses 8 feet per inch, which is the 1/8-inch scale. Convert each side first, then multiply. Worked arithmetic.
Question 9 · Basic Construction
A load worksheet asks for the "fenestration area" of a south wall that has windows but no doors. What do you measure?
- A. The framed wall area between studs
- B. The floor area of the south rooms
- C. The chimney chase
- D. The window openings
Show answer and explanation for question 9
Answer: D. The window openings.
Fenestration includes windows and skylights, openings in the building envelope. For this wall, measure the window openings—not the opaque framing (A), floor (B) or chimney chase (C). Window assemblies generally have lower thermal resistance than insulated opaque walls, so their area matters in heating and cooling calculations. Source: U.S. DOE Building Science Education — Fenestration, opening explanation.
Question 10 · Using Basic Science
A purely resistive heater circuit has 120 volts applied and draws 8 amps. What is its resistance?
- A. 0.067 Ω
- B. 15 Ω
- C. 112 Ω
- D. 960 Ω
Show answer and explanation for question 10
Answer: B. 15 Ω.
Ohm's law is V = I × R, so R = V ÷ I = 120 ÷ 8 = 15 Ω. A divides the wrong way (8 ÷ 120), C subtracts, and D multiplies. Check your answer: 8 A × 15 Ω = 120 V. Source: OpenStax University Physics Vol. 2, §9.4 Ohm's Law.
Question 11 · Using Basic Science
A loose lug on a contactor adds 0.1 Ω of resistance, and a steady DC load current of 30 A flows through it. How much power turns into heat at that connection?
- A. 3 W
- B. 90 W
- C. 300 W
- D. 900 W
Show answer and explanation for question 11
Answer: B. 90 W.
Power in a resistance is P = I² × R = 30² × 0.1 = 900 × 0.1 = 90 W, all of it concentrated at one small connection. That concentrated heating can damage the connection. A forgets to square the current (30 × 0.1). C divides (30 ÷ 0.1). D squares the current but never multiplies by the resistance. Source: OpenStax University Physics Vol. 2, §9.5 Electrical Energy and Power.
Question 12 · Using Basic Science
A sealed, rigid cylinder holds only refrigerant vapor (no liquid). In this paper model, treat the vapor as an ideal gas and keep its amount fixed as it warms up. What happens to the pressure inside?
- A. It rises
- B. It falls
- C. It stays the same because the volume can't change
- D. It drops to zero
Show answer and explanation for question 12
Answer: A. It rises.
With the volume and the amount of gas fixed, ideal-gas pressure rises in proportion to absolute temperature (Amontons's law, also taught as Gay-Lussac's law). Use kelvin and absolute pressure for that relationship. The fixed volume in C is exactly why the pressure has to go up, rather than staying constant. B reverses the relationship; D does not follow from warming the gas. Source: OpenStax Chemistry 2e, §9.2, pressure–temperature relationship.
Question 13 · Achieving Desired Conditions
Two houses both have a measured room dry-bulb air temperature of 75 °F. In one, the occupants say it feels sticky. Which condition most likely differs?
- A. Humidity
- B. Dry-bulb air temperature
- C. Barometric pressure
- D. Supply voltage
Show answer and explanation for question 13
Answer: A. Humidity.
Comfort depends on more than air temperature. ASHRAE Standard 55 lists six factors: metabolic rate, clothing insulation, air temperature, radiant temperature, air speed and humidity. With the same measured air temperature, "sticky" points to moisture. B is held equal by the question; barometric pressure (C) and supply voltage (D) do not describe the moisture difference. Source: ASHRAE's Standard 55 overview, environmental and personal factors; OpenStax §13.6, humidity and evaporative cooling.
Question 14 · Achieving Desired Conditions
During a routine indoor-air-quality review, solvent emissions are traced to containers stored in a utility closet next to the return. There is no spill or emergency. According to the EPA, which strategy usually addresses indoor pollution most effectively?
- A. Increase ventilation
- B. Add an air cleaner
- C. Raise the blower speed
- D. Remove or reduce the source
Show answer and explanation for question 14
Answer: D. Remove or reduce the source.
The EPA says source control is usually the most effective way to improve indoor air quality. Ventilation (A) dilutes pollutants; air cleaning (B) removes pollutants only to the extent the equipment is designed to capture them. Neither removes the source itself. Raising blower speed (C) does not by itself eliminate the emissions or introduce outdoor air. Source: EPA, Improving Indoor Air Quality — Source Control, Improved Ventilation, and Air Cleaners/Filtration.
Question 15 · Achieving Desired Conditions
Which indoor air quality strategy lowers pollutant levels by bringing in cleaner outdoor air?
- A. Source control
- B. Air cleaning
- C. Ventilation
- D. Reheat
Show answer and explanation for question 15
Answer: C. Ventilation.
Ventilation dilutes indoor pollutants with outdoor air. Source control removes or reduces what's giving off the pollutant, and air cleaning captures pollutants from indoor air. Reheating indoor air alone (D) does not bring in outdoor air. Source: EPA, Improving Indoor Air Quality.
Question 16 · Taking Temperature and Humidity Measurements
A digital thermometer set to Celsius reads 35 °C at a supply register. What is that in Fahrenheit?
- A. 63 °F
- B. 67 °F
- C. 95 °F
- D. 120.6 °F
Show answer and explanation for question 16
Answer: C. 95 °F.
°F = (°C × 1.8) + 32 = (35 × 1.8) + 32 = 63 + 32 = 95 °F. A stops before adding 32, B only adds 32, and D adds 32 before multiplying. The order matters. Source: NIST, SI Units – Temperature.
Question 17 · Taking Temperature and Humidity Measurements
Two rooms both read 50% relative humidity. One is at 68 °F and the other is at 86 °F. Which room's air holds more water vapor per cubic foot?
- A. The 68 °F room
- B. Both hold the same amount, because the percentage is the same
- C. Neither holds water vapor at 50%
- D. The 86 °F room
Show answer and explanation for question 17
Answer: D. The 86 °F room.
Relative humidity compares the water-vapor density with the saturation vapor density at the same temperature. At 86 °F, that saturation density is higher than at 68 °F, so 50% of a bigger number is more water. The same percentage (B) doesn't mean the same amount of moisture at different temperatures. A reverses the comparison; 50% relative humidity does not mean zero water vapor (C). Source: OpenStax College Physics 2e, §13.6 Humidity, Evaporation, and Boiling.
Question 18 · Taking Temperature and Humidity Measurements
Sunlight through a south window warms the carpet, even though the air between the glass and the floor stays cool. Which kind of heat transfer is this?
- A. Conduction
- B. Radiation
- C. Convection
- D. Latent heat transfer
Show answer and explanation for question 18
Answer: B. Radiation.
Radiation moves heat as electromagnetic energy, such as sunlight and infrared, and doesn't need the air in between to carry it. Conduction (A) needs physical contact. Convection (C) needs a moving fluid such as air. Latent heat (D) is energy tied to a change of state, like evaporating or condensing water; no phase change is described here. Source: OpenStax College Physics 2e, §14.4 Heat Transfer Methods; §14.3 Phase Change and Latent Heat.
Question 19 · Basic Electrical
On a paper circuit diagram, where should a voltmeter be shown to measure voltage across a contactor coil?
- A. In parallel, one lead on each coil terminal
- B. In series with the coil
- C. One lead on the coil, the other on the meter's case
- D. Across the fuse only
Show answer and explanation for question 19
Answer: A. In parallel, one lead on each coil terminal.
A voltmeter connects in parallel with the part it measures. Its internal resistance is very high, so it barely changes the circuit. Placing it in series (B) puts that high resistance in the coil's path and changes the circuit being tested. The meter's case (C) is not a coil terminal. Across the fuse (D) measures the fuse's voltage drop, not the coil's. Source: OpenStax University Physics Vol. 2, §10.4 Electrical Measuring Instruments.
Question 20 · Basic Electrical
Power is off and verified, and the capacitors are discharged. You measure a resistor marked 100 Ω while it's still soldered into a control board, and your meter reads 60 Ω. What's the best explanation?
- A. The resistor has definitely failed low
- B. Resistance can only be read accurately with the circuit powered
- C. Reversing the meter leads will bring the reading back to 100 Ω
- D. Other components in parallel with it can pull the reading down, so test it out of circuit before condemning it
Show answer and explanation for question 20
Answer: D. Other components in parallel with it can pull the reading down, so test it out of circuit before condemning it.
Anything connected in parallel with the part you're testing affects the reading, usually lowering it. Fluke's guidance is to check the schematic for parallel paths and to test the component out of the circuit for the best result. A jumps to a conclusion the reading can't support. B is backwards: resistance is measured with power off. C doesn't remove the parallel path. Source: Fluke, How to Measure Resistance with a Digital Multimeter.
Question 21 · Basic Electrical
A 4 Ω resistor and an 8 Ω resistor are wired in series across a 24-volt DC source. What is the voltage across the 8 Ω load?
- A. 8 V
- B. 12 V
- C. 16 V
- D. 24 V
Show answer and explanation for question 21
Answer: C. 16 V.
Series resistances add: 4 + 8 = 12 Ω. Current = 24 ÷ 12 = 2 A, and it's the same through both loads. Voltage across the 8 Ω load = 2 × 8 = 16 V, and across the 4 Ω load = 2 × 4 = 8 V. Check: 16 + 8 = 24 V. A gives the voltage across the other resistor. B splits the voltage evenly, which only works for equal loads. D would be true in parallel. Sources: OpenStax §10.2 Resistors in Series and Parallel; §9.4 Ohm's Law.
Question 22 · Basic Electrical
A rung on a ladder diagram reads: L1 — high-pressure switch (normally closed) — low-pressure switch (normally closed) — contactor coil — L2. The coil is initially energized, the low-pressure switch stays closed, and this rung is the coil's only supply path. The high-pressure switch opens. What happens to the contactor coil?
- A. It stays energized through the low-pressure switch
- B. It receives double voltage
- C. It de-energizes
- D. The low-pressure switch opens too
Show answer and explanation for question 22
Answer: C. It de-energizes.
The two switches and the coil are in series, so there is one path for current. An opening anywhere in a series path stops current through all of it, and the contactor drops out. In this diagram, either series switch can interrupt the coil's supply. Opening a switch does not double the source voltage (B). Switches in series can't bypass each other (A), and one switch opening doesn't change the other's position (D). Source: OpenStax §10.2 Resistors in Series and Parallel.
Question 23 · Basic Electrical
A paper control circuit has a healthy 24-volt transformer secondary, one switch and an intact relay coil in a single series loop. The switch is the only open point. With a high-input-resistance voltmeter, which component will have approximately 24 V across it?
- A. Across the open switch
- B. Across the relay coil
- C. Nowhere — with the switch open the circuit is dead
- D. 24 V across the coil and another 24 V across the switch
Show answer and explanation for question 23
Answer: A. Across the open switch.
Ignoring the meter's tiny current, the open switch stops current, so the intact coil has essentially no voltage drop (B). Around the loop, the voltage drops must still add up to the source voltage, so approximately 24 V appears across the open switch. That conclusion depends on the single-open, intact-coil conditions given here; it is not a rule for every control circuit. C confuses "no current" with "no voltage", and D would add up to 48 V from a 24 V source. Sources: OpenStax §10.3 Kirchhoff's Rules; §10.4 Electrical Measuring Instruments.
Question 24 · Basic Electrical
Two steady DC loads are connected in parallel on the same supply. One draws 5 A and the other draws 7 A. What current flows in the supply conductor feeding both?
- A. 2 A
- B. 5 A
- C. 7 A
- D. 12 A
Show answer and explanation for question 24
Answer: D. 12 A.
All the current flowing into a junction has to flow out of it, so the feeder carries 5 + 7 = 12 A. A subtracts, and B and C count only one branch. Source: OpenStax University Physics Vol. 2, §10.3 Kirchhoff's Rules.
Question 25 · Basic Electrical
An electric heat element is rated 4,800 W at 240 V. It's installed on a 208 V supply. Treating its resistance as fixed, about how much power does it put out?
- A. 4,800 W
- B. 4,160 W
- C. 3,605 W
- D. 2,400 W
Show answer and explanation for question 25
Answer: C. 3,605 W.
First find the resistance: R = V² ÷ P = 240² ÷ 4,800 = 57,600 ÷ 4,800 = 12 Ω. At 208 V: P = V² ÷ R = 43,264 ÷ 12 ≈ 3,605 W. Power depends on the square of voltage, so about a 13% voltage drop costs about 25% of the heat. B scales power in step with voltage. A ignores the lower voltage. D halves the original power, which is not the result for 208 V at the stated fixed resistance. Source: OpenStax University Physics Vol. 2, §9.5 Electrical Energy and Power.
Score your set
Count your correct answers in each topic. Leave unanswered questions unmarked and record how many you attempted:
| Core topic | Questions on this page | Your correct |
|---|---|---|
| Safety | 1–5 (5) | ___ |
| Tools | 6–7 (2) | ___ |
| Basic Construction | 8–9 (2) | ___ |
| Using Basic Science | 10–12 (3) | ___ |
| Achieving Desired Conditions | 13–15 (3) | ___ |
| Taking Temperature and Humidity Measurements | 16–18 (3) | ___ |
| Basic Electrical | 19–25 (7) | ___ |
Your total tells you how you did on these 25 questions. It isn't a NATE score, and it can't predict a pass: these small topic samples cannot establish readiness. Use your misses to decide what to study first. The review map below gives you a place to start.
My tally: ___ correct out of ___ answered; ___ of 25 questions attempted. These are this page's item counts, not NATE's exam weights.
What to review next
Use your missed questions to choose a topic, then check the outline for your exact exam. NATE's outlines are called KATEs, short for Knowledge Areas of Technician Expertise; they identify an exam's topics, concepts, skills and reference resources, but do not teach the material themselves (NATE's KATE index).
The seven topic names below follow NATE's Traditional Pathway overview. The drill lists are editorial study prompts, not a complete official blueprint or an estimate of how many questions you will see.
| Core topic | What to drill first | Start here |
|---|---|---|
| Basic Electrical | Reading schematic (ladder) diagrams for sequence, meter setups for volts/ohms/amps, single- and three-phase motors, electronically commutated motors (ECMs), damper actuators | Questions 19–25; Worked example 1 |
| Safety | Lockout/tagout, ladders, brazing gases and oxy-acetylene, SDS and hazmat, cylinder handling, confined spaces, moving machinery | Questions 1–5 |
| Achieving Desired Conditions | Temperature and humidity for comfort, ventilation and air cleaning, odor control, equipment and airflow noise | Questions 13–15 |
| Taking Temperature and Humidity Measurements | Sensible vs. latent heat, BTU, conduction/convection/radiation, thermometer types and calibration, sling psychrometer, psychrometric chart, enthalpy | Questions 16–18 |
| Using Basic Science | Ohm's law, series and parallel circuits, power and power factor, pressure and gas laws, HVAC math (fractions, algebra, geometry, graphs) | Questions 10–12; both worked examples |
| Tools | Measurements and tolerances, fabrication tools, tubing tools (cutters, flaring, swaging, benders, reamers) | Questions 6–7 |
| Basic Construction | Plans and specifications, scale drawings, walls, floors, roofs, trusses, fenestration, chimneys | Questions 8–9 |
Download the current outline for your exam from NATE's outline page when you start studying. This set reviews selected foundations; it does not cover every outline topic.
Worked example 1: the voltage that never reaches the load
This one shows why a load can see less than the source voltage.
A 24-volt DC source feeds a 48 Ω resistive load. A corroded connection adds 12 Ω in series. How much voltage reaches the load?
- Total resistance: 12 + 48 = 60 Ω.
- Current: 24 V ÷ 60 Ω = 0.4 A. It's the same everywhere in a series loop.
- Voltage across the bad connection: 0.4 A × 12 Ω = 4.8 V.
- Voltage across the load: 0.4 A × 48 Ω = 19.2 V.
- Check: 4.8 + 19.2 = 24 V.
Answer: 19.2 V. The source reads a healthy 24 V, but the load gets 19.2 V because 4.8 V is used up at the bad connection. The voltage across the load, not just the source voltage, is what answers this question. This is a simple resistor model on paper. Don't treat an operating AC motor as a fixed resistance. Sources: OpenStax §10.2; §9.4.
Worked example 2: convert duct size before you multiply
Airflow math combines geometry and units.
A rectangular duct measures 18 in × 12 in inside. The average air velocity across it is 480 feet per minute (fpm). What is the airflow in cubic feet per minute (CFM)?
- Convert each side to feet: 18 ÷ 12 = 1.5 ft; 12 ÷ 12 = 1 ft.
- Area: 1.5 ft × 1 ft = 1.5 sq ft.
- Airflow = area × average velocity: 1.5 sq ft × 480 ft/min = 720 cubic ft/min.
Answer: 720 CFM. Follow the units: square feet × feet per minute = cubic feet per minute. If you multiply 216 square inches by 480, you get 103,680, a number that's wrong by a factor of 144. The formula needs the average velocity across the whole opening; one reading taken at one spot isn't necessarily that. Source: OpenStax College Physics 2e, §12.1 Flow Rate and Its Relation to Velocity.
Which NATE exam are you studying for?
Study for the exam you'll actually sit. This page focuses on the Core, which technicians on the traditional route take along with one specialty exam.
| Route | What you take | How to use this page |
|---|---|---|
| Traditional | Core + one Specialty: a 50-question Core exam and a 100-question Specialty exam | Use these 25 questions for selected Core foundations; study the separate outline for your specialty. |
| CHP-5 (Certified HVAC Professional) | Five 30-question exams: HVAC Fundamentals, Electrical and Controls, Comfort and Airflow, Installation, Service | Use relevant foundation questions as extra review, not as a complete CHP-5 practice exam. Match further study to the KATE for the exam you booked. |
| Entry-level certificates | Ready-to-Work; HVAC Support Technician | These are separate entry-level assessments, not interchangeable with the Traditional or CHP-5 pathway. Use their own outlines. |
Sources: NATE Traditional Pathway; NATE Getting Started, certification options; NATE’s CHP-5 pathway summary.
On CHP-5? You can take the five exams in any order, with up to six months between them (NATE’s CHP-5 pathway summary). Start with the KATE for your named subject. Do not assume that a Core topic label defines the content or weighting of a CHP-5 exam.
Picking a specialty? Choose the equipment you actually install or service. The installation specialties are Air Conditioning, Air Distribution, Air-to-Air Heat Pump and Gas Heating (Air). The service specialties add Hydronics Gas, Hydronics Oil, Light Commercial Refrigeration, Commercial Refrigeration and Oil Heating (Air). NATE lists those options on its Traditional Pathway page. Each has its own outline on NATE's outline page.
Still choosing a route, or sorting out booking and cost? Our NATE certification guide covers pathways, booking, what happens if you fail, and renewal.
Your 4-week NATE Core study plan
This plan assumes about 5 hours a week (five 1-hour sessions) while you're working full time — 20 hours in all. That's a study budget, not a promise that 20 hours is enough; stretch any week you find hard. The order below is an editorial study sequence, not an allocation of official exam weights.
Run each session the same way: 10 minutes recalling the last session without notes, 35 minutes on the task, 15 minutes explaining your answers out loud and updating your mistake log.
Week 1: Basic Electrical + Using Basic Science
| Session | Task |
|---|---|
| 1 | Take all 25 questions above, cold. Start your mistake log. |
| 2 | Work Worked example 1, then redo Questions 10, 11, 21 and 25. Write P = I × V, P = I² × R and P = V² ÷ R from memory for a resistive circuit. |
| 3 | Take the wiring diagram from a unit you service, or use the paper circuit in Question 22. Redraw one control circuit as a ladder rung and trace what energizes the contactor. Redo Questions 22 and 23. Keep this a paper exercise, not live electrical work. |
| 4 | Meters: show volts in parallel and an ammeter in series on a paper diagram; resistance testing requires power off and verified, with capacitors discharged. Redo Questions 19 and 20, then Question 24 on current in parallel branches. |
| 5 | Walk the electrical and basic-science headings in the Core outline. Mark anything you can't explain yet. Use the review map to check gaps such as motor types and power factor against that outline, then study those from your training materials. |
Week 2: Safety + Tools + Basic Construction
| Session | Task |
|---|---|
| 6 | Read the OSHA sections linked in Questions 1–5. |
| 7 | Pull the SDS for a refrigerant you carry and find Sections 2, 4 and 8. Review brazing and cylinder safety. |
| 8 | Fractions, decimals and metric conversions: do 10 of your own from the tape and spec sheets. Redo Questions 6 and 7. |
| 9 | Take a real mechanical plan, or reuse the scale and room dimensions in Question 8. Find the scale, then work out two lengths and one room area. Redo Questions 8 and 9. |
| 10 | Walk the Safety, Tools and Basic Construction outline headings and mark gaps. Use the review map to prompt checks such as tubing tools, confined spaces and framing terms; the exam's own outline determines the additional study you need. |
Week 3: Comfort + Temperature and Humidity
| Session | Task |
|---|---|
| 11 | Sensible vs. latent heat and the three transfer methods, with one example of each from your jobs. Redo Questions 17 and 18; use the linked phase-change and heat-transfer lessons to check your explanations. |
| 12 | Psychrometric chart: using the chart and a worked exercise from your training materials, practice finding relative humidity, dew point and enthalpy from the supplied readings under that exercise's conditions. For a starting review here, explain why Question 17 has different moisture amounts at equal relative humidity; use its linked lesson to check the meaning of dew point. |
| 13 | Work Worked example 2, plus °C/°F conversions. Redo Question 16. |
| 14 | Indoor air quality and comfort: source control, ventilation, air cleaning, humidity and noise. Redo Questions 13–15. |
| 15 | Walk the Achieving Desired Conditions and Taking Temperature and Humidity Measurements outline sections and mark gaps. Check the review map's prompts, including thermometer calibration, enthalpy and noise sources, against your outline. |
Week 4: Review and book
| Session | Task |
|---|---|
| 16 | Retake all 25 with the answers covered. |
| 17 | Rework every miss and every lucky guess from your log. |
| 18 | Walk the whole Core outline bullet by bullet; say out loud what each one means. |
| 19 | Study your two weakest outline headings from your own notes and training materials. |
| 20 | Confirm your exam details (see "Before test day") and book or confirm the date. |
A second pass through these same 25 questions may score higher partly because you've seen them. Treat it as a check on your explanations, not a readiness test.
If you have less time, failed once, or also need a specialty
- Two weeks: double up — two sessions a day, five days a week. It's the same 20 hours, just packed tighter. Use that schedule only when two hours a day leaves enough time to understand and explain the work.
- Retaking after a fail: use any topic feedback in your score report alongside your mistake log to identify concepts to revisit. Do not turn a reported percentage into an exact number of lost questions. Spend weeks 1 and 4 on the gaps you still cannot explain or solve.
- Adding a specialty: the Core and the specialty are separate exams. Build additional study sessions around that specialty's own outline; this Core plan does not set a sufficient preparation time for a specialty.
Keep a mistake log
Before you read an explanation, write down your answer and why you chose it. Your reason tells you what to fix.
| Question or outline topic | My answer and why | The correct idea | Type of mistake | What I'll do next |
|---|---|---|---|---|
| Q25 (example) | "4,160 W. I cut the power by the same percentage as the voltage." | Power follows voltage squared: find R first, then P = V² ÷ R ≈ 3,605 W. | Formula | Redo Q11 and Q25; write the three power formulas from memory tomorrow. |
| Your next miss | Concept / formula / units / arithmetic / misread question |
Log lucky guesses too. A right answer you can't explain is a miss waiting to happen.
Before test day
NATE offers in-person testing through testing organizations and remote Live Online Proctoring (NATE Getting Started, Take Your NATE Exams). Use the current instructions for the exam and delivery method you booked.
For either delivery method: confirm your exact exam name, start time and time zone, duration, ID and check-in requirements, permitted calculator and materials, accommodation arrangements, and rescheduling terms. Use your booking confirmation and testing organization's instructions rather than this practice set as the authority for those rules.
Testing remotely? Complete the system and workspace checks required by your booking instructions, and check their rules for scratch paper, breaks and software before exam day.
Testing in person? Ask your testing organization about calculators, allowed materials, ID and check-in, and fees. NATE's Getting Started page links to its testing-location search and remote-testing information.
Either way, double-check that the exam you booked matches the outline you studied.
Quick answers
Are these real NATE questions? No. The questions on this page are original, unofficial practice. Their explanations cite public technical sources; they are not NATE test items and do not reproduce an official exam form.
Does NATE certification replace EPA 608 certification? No. EPA Section 608 is a separate federal certification for covered refrigerant work. You earn it by passing an EPA-approved test; EPA also explains the exemption for apprentices closely and continually supervised by a certified technician (EPA requirements). Our EPA 608 guide covers that exam.
Where is the official exam outline? Use NATE's free KATE index and select the exact exam name. The outline is a topic checklist, not a substitute for learning the concepts or working practice problems.
Sources
NATE (pathways, topic names and official outlines)
- Traditional Pathway — Core and Specialty question counts, the seven broad Core topic names, and specialty options
- NATE exam outlines (KATE index) — the purpose of KATEs and links to exam-specific outlines
- Getting Started — Traditional, CHP-5 and entry-level distinctions; the five CHP-5 subject names; in-person and remote testing options
- NATE’s CHP-5 pathway summary — the exam owner’s publication on the five 30-question exams, their order and the interval between them
Federal rules and technical references (practice answers)
- OSHA 1910.147 lockout/tagout · 1910.1200 Appendix D: safety data sheets · 1926.1053 ladders · 1926.350 gas welding and cutting · 1910.253 oxygen-fuel gas welding and cutting
- NIST SI Units – Length · SI Units – Temperature
- EPA, Improving Indoor Air Quality · EPA Section 608 certification requirements
- U.S. DOE, Fenestration · ASHRAE, Standard 55 overview
Physics references (practice answers and worked examples)
- OpenStax University Physics Vol. 2: §9.4 Ohm's Law · §9.5 Electrical Energy and Power · §10.2 Resistors in Series and Parallel · §10.3 Kirchhoff's Rules · §10.4 Electrical Measuring Instruments
- OpenStax College Physics 2e: §12.1 Flow Rate · §13.6 Humidity · §14.3 Phase Change and Latent Heat · §14.4 Heat Transfer Methods
- OpenStax Chemistry 2e, §9.2 The Ideal Gas Law
- Fluke, How to Measure Resistance with a Digital Multimeter
Last source-checked September 28, 2026: the NATE pathway structure, broad topic names and KATE index cited above, plus the technical principles linked with the questions and worked examples. Calculations were rechecked separately. This date does not certify complete alignment with every current exam outline.
By the Castleport Test Prep Editorial Team.
This resource was developed with AI assistance and source checking, not a named professional review. Read our methodology.
Castleport Test Prep is an independent exam prep publisher. We are not affiliated with, endorsed by, or approved by North American Technician Excellence (NATE). The practice questions on this page are original and are not NATE exam questions. Exam and credential names are used to identify their subjects; trademarks belong to their respective owners.