NCCER Case Analysis & Practical Application 2 — Questions and Answers
Question 1: A homeowner reports that a GFCI outlet in their bathroom keeps tripping immediately after being reset. What is the most likely cause?
- The circuit is overloaded with too many devices
- There is a ground fault or moisture in the circuit downstream of the GFCI (Correct answer)
- The GFCI device itself has failed and needs replacement
- The circuit breaker in the panel is faulty
Correct answer: There is a ground fault or moisture in the circuit downstream of the GFCI
A GFCI that trips immediately after reset typically indicates a ground fault or moisture downstream in the protected circuit.
Question 2: You are repairing a wooden deck and find that several joists have soft, spongy areas near the ledger board. What should you do first?
- Apply waterproof sealant to the affected areas immediately
- Replace the ledger board flashing to stop ongoing moisture intrusion before any structural repair (Correct answer)
- Sistering the damaged joists with new lumber right away
- Coat the joists with wood hardener and monitor for six months
Correct answer: Replace the ledger board flashing to stop ongoing moisture intrusion before any structural repair
Addressing the source of moisture (improper flashing at the ledger board) must come before structural repairs, or the new material will rot as well.
Question 3: A customer asks you to hang a 200-lb mirror on a plaster wall. Your stud finder cannot locate studs reliably. What is the best approach?
- Use the largest toggle bolts available rated for the load
- Use a magnetic stud finder to find nail patterns indicating stud locations
- Drive a small pilot hole to probe for solid backing, then use wood screws into studs
- Mount a backing board across multiple studs and attach the mirror to the board (Correct answer)
Correct answer: Mount a backing board across multiple studs and attach the mirror to the board
For very heavy loads on plaster, a backing board spanning multiple studs distributes weight safely and provides reliable anchoring.
Question 4: While snaking a clogged kitchen drain, you encounter solid resistance about 20 feet in that the snake cannot break through. What does this most likely indicate?
- A grease buildup that needs chemical treatment
- A collapsed or offset pipe section requiring camera inspection (Correct answer)
- The snake has reached the main stack
- A root intrusion that can be cleared with a larger snake
Correct answer: A collapsed or offset pipe section requiring camera inspection
Solid immovable resistance at a specific distance often indicates a collapsed or severely offset pipe that requires video inspection before further action.
Question 5: A customer complains that their forced-air furnace runs continuously but the house never reaches the set temperature in winter. After confirming the thermostat is accurate, what should you check next?
- Replace the thermostat with a smart model
- Inspect and replace the furnace filter, then check for duct leaks (Correct answer)
- Upgrade the furnace to a higher BTU rating
- Add a second thermostat in the coldest room
Correct answer: Inspect and replace the furnace filter, then check for duct leaks
A clogged filter or significant duct leakage are the most common causes of a furnace running constantly without meeting the setpoint.
Question 6: You notice that a newly installed exterior door has a consistent 1/4-inch gap at the top corner on the latch side. What adjustment should you make?
- Add weatherstripping to the door stop on that corner
- Adjust the top hinge by adding a shim to move the door closer to the frame on the latch side (Correct answer)
- Replace the strike plate with a longer version
- Plane down the top edge of the door on the latch side
Correct answer: Adjust the top hinge by adding a shim to move the door closer to the frame on the latch side
A gap at the top latch-side corner means the door is leaning away there; shimming the top hinge pivots the top of the door toward the frame.
Question 7: A homeowner has a slow-draining bathroom sink. After removing and cleaning the pop-up assembly stopper, the drain is still slow. What is the next logical step?
- Replace the entire drain assembly
- Use a hand auger or drain snake to clear the P-trap and branch drain (Correct answer)
- Pour drain cleaner into the drain and wait 24 hours
- Replace the sink because it may have a defective drain slope
Correct answer: Use a hand auger or drain snake to clear the P-trap and branch drain
After confirming the stopper is clear, the blockage is likely in the P-trap or branch drain and should be mechanically cleared with an auger.
NCCER Case Analysis & Practical Application 2
A homeowner reports that a GFCI outlet in their bathroom keeps tripping immediately after being reset.
What is the most likely cause?