CFB Blueprint Reading & Interpretation 3 — Questions and Answers
Question 1: On electrical drawings, what does the symbol for a duplex outlet (two parallel lines with a circle) represent?
- A single-pole switch
- A standard 120V duplex receptacle (Correct answer)
- A 240V appliance connection
- A ground fault circuit interrupter panel
Correct answer: A standard 120V duplex receptacle
The standard symbol of two parallel lines with a circle represents a duplex (two-outlet) 120V wall receptacle on electrical plans.
Question 2: What does 'AFF' stand for in construction drawings?
- All Framing Fixed
- Above Finished Floor (Correct answer)
- Approved Final Form
- Anchor Foundation Footing
Correct answer: Above Finished Floor
AFF means 'Above Finished Floor' and is used to define the height of features like outlets, switches, or handrails measured from the finished floor surface.
Question 3: In a structural steel drawing, what does 'W8×31' designate?
- A wide-flange beam 8 inches deep weighing 31 pounds per linear foot (Correct answer)
- A wall panel 8 feet wide with 31 anchors
- A weld type with 8mm throat and 31mm length
- A web plate 8 inches high with 31 holes
Correct answer: A wide-flange beam 8 inches deep weighing 31 pounds per linear foot
W-shape designations list the nominal depth in inches followed by the weight per linear foot, so W8×31 is a wide-flange section 8" deep at 31 lb/ft.
Question 4: A detail drawing on a blueprint is used to:
- Show the entire project site at a small scale
- Provide a large-scale view of a specific, complex portion of the design (Correct answer)
- List all material quantities for the project
- Display the overall floor plan layout
Correct answer: Provide a large-scale view of a specific, complex portion of the design
Detail drawings zoom in on complex connections or assemblies to provide precise construction information that would be unclear at the sheet's overall scale.
Question 5: When a drawing calls out 'NTS,' what should the field builder understand?
- Not to scale — do not scale measurements from this drawing (Correct answer)
- New temporary structure required
- No thread specification for fasteners
- Night-time shift work required
Correct answer: Not to scale — do not scale measurements from this drawing
'NTS' (Not to Scale) warns that the drawing is a schematic or diagram and that dimensions must come from noted values, not from measuring the paper.
Question 6: On a plumbing riser diagram, flow direction is most commonly indicated by:
- The thickness of the pipe line
- Arrows along the pipe line (Correct answer)
- Pipe color coding only
- The dashed-line pattern
Correct answer: Arrows along the pipe line
Arrows placed along pipe runs on riser diagrams show the intended direction of flow through the system.
Question 7: What is the purpose of a revision block (or revision triangle) on a construction drawing?
- To list all subcontractors involved
- To record changes made to the drawing after initial issue (Correct answer)
- To show which inspector approved the plan
- To identify the drawing scale used
Correct answer: To record changes made to the drawing after initial issue
Revision blocks track amendments to a drawing, listing the revision number, date, description of change, and initials of the responsible party.
CFB Blueprint Reading & Interpretation 3
On electrical drawings, what does the symbol for a duplex outlet (two parallel lines with a circle) represent?