General Plumbing Knowledge, Tools, and Safety
General Plumbing Knowledge, Tools, and Safety
This domain tests whether you can select materials and tools correctly and work without creating hazards. Expect questions on joining methods, test equipment, trench and ladder safety, and fire protection during soldering or brazing.
Core rules and concepts
- Match the joining method to the material: solder or press for copper, solvent cement for PVC and CPVC, crimp or expansion for PEX, and hubless couplings for cast iron.
- Use a tubing cutter for copper and plastic, a soil pipe cutter for cast iron, and a press tool with the correct jaw and calibration for press fittings.
- Test gauges must be rated above the test pressure and readable in the expected range; a 0 to 200 psi gauge is better than a 0 to 600 psi gauge for a 100 psi water test.
- Trenches 5 ft or deeper require a protective system; spoil and tools stay back from the edge; ladders extend 3 ft above the landing and are secured.
- Soldering and brazing require a fire watch, shielding, and clearance from combustibles; never solder a line that has not been purged or that contains trapped water.
Worked example
A 6 ft deep trench is dug for a building sewer. Because the depth exceeds 5 ft, a protective system is required. The spoil pile is placed 2 ft from the edge, and a ladder is set every 25 ft of travel. The reasoning: the 5 ft trigger is about cave-in protection, while spoil setback reduces surcharge loading and edge collapse.
Traps that cost marks
Using a wheel cutter on cast iron, pressing a fitting with the wrong jaw, testing plastic DWV with uncontrolled air pressure, leaving a ladder unsecured, and assuming PPE replaces engineering controls.