G3 Cheat Sheet 2026

The 30 highest-yield G3 facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. How must gas appliances in sleeping rooms be installed? → Only direct-vent (sealed combustion) appliances are generally permitted
2. What is the difference between complete and incomplete combustion? → Complete produces CO2 and water; incomplete produces CO and soot
3. What are the requirements for gas appliance clearances from bath and shower areas? → Specific clearances from bath/shower areas as specified in CSA B149
4. What document must a G3 technician carry while performing gas work on site? → Their TSSA-issued certificate or wallet card
5. What should technicians do if a gas leak is detected during an inspection? → Shut off the gas supply and follow safety protocols
6. What happens to natural gas volume when temperature increases at constant pressure? → Volume increases proportionally (Charles's Law)
7. What is the first step in registering for the Gas Technician Level 3 certification exam? → Submitting proof of training and application
8. What is the specific gravity (or relative density) of a gas a measure of? → The ratio of the gas's density to the density of air.
9. What leak detection method is used after completing a gas piping installation? → Applying approved leak detection solution to all joints and connections
10. What type of electronic leak detector is best suited for detecting very small leaks in high-pressure gas distribution mains? → Flame ionization detector (FID)
11. What study strategies are recommended for G3 exam preparation? → Combining code book familiarity, concept understanding, and scenario-based practice
12. What should a candidate do if they fail the G3 exam? → Wait 30 days before rescheduling
13. What is the primary purpose of a draft hood on a gas appliance? → To provide a safety break preventing excessive draft and backdraft
14. What is the purpose of a flame rollout switch? → To detect flames burning outside the combustion chamber and shut off gas
15. How should substandard work by another technician be handled? → Document professionally, explain factually, report safety hazards to TSSA
16. What is a draft gauge used for? → Measuring draft (pressure difference) in the vent system
17. Electronic combustible gas detectors measure gas concentration as a percentage of which value? → Lower explosive limit (LEL)
18. How does propane's flue gas dew point compare to natural gas? → Propane has a higher dew point (~59°C) than natural gas (~54°C)
19. What is required to maintain certification after passing the Gas Technician Level 3 exam? → Completing continuing education courses
20. What is the minimum test pressure typically required for a pressure integrity test on a residential gas piping system according to most North American codes? → 10 psi
21. Which topics carry the most weight on the G3 exam? → Gas codes, safety, and combustion principles
22. What is the purpose of the practical assessment in the Gas Technician Level 3 certification process? → To assess practical application of skills
23. What is the purpose of a barometric damper? → To regulate draft by allowing room air in when draft is excessive
24. What does compliance with local codes and regulations ensure during gas system installations? → Adherence to safety and legal standards
25. Which condition requires a technician to tag out and NOT restore gas service after completing a leak test? → A leak is found that cannot be repaired with available tools and materials on site
26. Which prerequisite must be completed before writing the G3 certification exam? → Completion of an approved training program
27. What is the foundational principle of professional standards and ethics in the Gas Technician Level 3 Certification field? → Maintaining competence, integrity, and service to stakeholders
28. What should be done if carbon monoxide exposure is suspected in a building occupant? → Move to fresh air, call 911, shut down suspected source
29. What safety device prevents gas flow if a standing pilot goes out? → Thermocouple and gas valve safety circuit
30. What is the primary purpose of CSA B149.1? → Establishing installation requirements for natural gas and propane equipment