308A Cheat Sheet 2026

The 30 highest-yield 308A facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the recommended method for cutting galvanized steel to minimize exposure to zinc fumes? → Use mechanical cutting methods such as shears, snips, or plasma with proper ventilation
2. What do hidden lines (dashed lines) represent on a sheet metal blueprint? → Edges, surfaces, or features that are not visible from the current viewing angle
3. What is the purpose of 'cross-breaking' a sheet metal panel? → To add rigidity by creating a slight diagonal crease across the panel surface
4. What is the standard practice when transferring a pattern from a template to sheet metal? → Scribe the outline with a scratch awl or prick punch the key points
5. What is the maximum recommended aspect ratio for rectangular ductwork according to SMACNA standards? → 8:1
6. Under Canadian OHS legislation, when is a sheet metal worker entitled to refuse unsafe work? → When performing the work would place the worker or others in imminent danger
7. What is the purpose of turning vanes in a rectangular duct elbow? → To reduce turbulence and pressure loss by guiding airflow smoothly around the turn
8. When developing a pattern for a Y-branch (lateral) fitting, which layout method is primarily used? → A combination of triangulation and radial line development
9. What is the 'neutral axis' in sheet metal bending? → The axis where the metal neither stretches nor compresses during bending
10. What does 'NTS' mean on a drawing and what precaution should be taken? → Not To Scale — do not measure dimensions from the drawing; use only the written dimensions
11. What does 'CFM' stand for and what does it measure in HVAC? → Cubic Feet per Minute — the volume of air flowing through the system
12. What does the abbreviation 'EL' followed by a number represent on an HVAC drawing? → Elevation — the height above a reference point, typically the finished floor
13. What is the ASHRAE recommended outdoor air ventilation rate for general office space? → 15 to 20 CFM per person
14. In radial line development, what type of object is typically being patterned? → A cone or frustum
15. When using a slip roll former, what determines the minimum diameter of a cylinder that can be formed? → The diameter of the upper (adjustable) roll
16. What type of welding process is most commonly used for joining sheet metal in HVAC fabrication? → Gas Metal Arc Welding (GMAW/MIG)
17. What personal protective equipment is mandatory when operating a power squaring shear? → Safety glasses, hearing protection, and no loose clothing or jewelry
18. What is a 'snap lock' seam used for in sheet metal fabrication? → Connecting round duct sections longitudinally with a self-locking seam that snaps together
19. What is the correct immediate procedure when a coworker sustains a laceration on a construction site? → Apply first aid, notify the supervisor, and complete an incident report
20. What is the purpose of a 'miter line' in an elbow pattern development? → To define the cut line where two sections of an elbow join together
21. What does a centerline (long dash-short dash pattern) indicate on a duct drawing? → The axis of symmetry, center of a round duct, or center of a feature like a hole
22. What is 'burring' in sheet metal work? → Turning a narrow flange or edge on the end of a round pipe or disc
23. What is the purpose of a 'standing seam' in sheet metal roofing and architectural work? → To create a raised, interlocking seam that sheds water and allows thermal movement
24. When must a journeyperson sheet metal worker produce their Red Seal Certificate of Qualification? → When requested by an employer, inspector, or regulatory authority
25. How is the true length of a line determined when it appears foreshortened in a plan view? → By constructing a true length diagram using the plan view length and the height difference
26. When operating a power squaring shear, what safety device prevents the operator's hands from entering the cutting area? → A holddown or finger guard assembly
27. A lockout/tagout (LOTO) procedure is required before performing which of the following tasks? → Performing maintenance or clearing jams on energized equipment
28. What is the minimum passing score required on the Red Seal Interprovincial Examination for Sheet Metal Worker 308A? → 70%
29. What is the maximum permitted duct leakage rate for a SMACNA Seal Class A system at 2" WG? → Approximately 1% of system airflow or less, as specified by CL = 6 formula
30. What type of gloves provide the best protection when handling sheet metal with sharp cut edges? → Cut-resistant gloves rated Level A4 or higher (ANSI/ISEA 105)