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These 10 free CA-C36 questions are organized by exam domain, so you can see how each part of the California C-36 Plumbing Contractor License Exam blueprint is tested. Reveal the answer and explanation under each question.
The layout for a 3-inch under-slab drain requires a minimum slope of 1/4 inch per foot over a 36-foot horizontal run. Field measurements give an upstream invert of 102.20 feet and a fixed downstream connection invert of 101.55 feet. What should the layout review conclude?
Correct answer: D - The route is 1.2 inches short of the required fall and needs revision.
A bathroom repipe is estimated at $1,800 for materials, two plumbers working 8 hours each at $75 per person-hour, $400 for equipment, and $600 for allocated overhead. The labor rate already includes payroll burden, and these are all the job costs. The contractor wants 20% of the selling price to remain after paying those costs. What price meets that target?
Correct answer: D - $5,000
A gas system will be sized by the longest-length method. After the furnace addition, the longest developed run from the meter to any outlet will be 72 feet. The new 18-foot branch serves only a furnace with 140,000 Btu/h input and 112,000 Btu/h output. The gas heating value is 1,000 Btu per cubic foot. The applicable pipe-sizing schedule gives the following capacities, in cubic feet per hour: 20-foot row: 1/2 inch = 118; 3/4 inch = 247; 1 inch = 466; 1-1/4 inches = 957. 80-foot row: 1/2 inch = 56; 3/4 inch = 117; 1 inch = 220; 1-1/4 inches = 452. Using this method, what is the smallest listed size for the new branch?
Correct answer: C - 1 inch
A 2-inch horizontal waste branch must join a 3-inch horizontal drain at a right angle. The proposed detail uses a sanitary tee with its run and branch lying in the horizontal plane. Which revision provides the proper drainage pattern?
Correct answer: D - Use a combination wye and one-eighth bend directed downstream.
A potable-water makeup line will remain directly connected to a commercial process loop containing a toxic corrosion inhibitor. The process pump can raise loop pressure above the incoming water pressure. The water supplier permits a listed mechanical backflow assembly for this connection. Which assembly addresses both the degree of hazard and the possible direction of backflow?
Correct answer: B - Reduced-pressure principle assembly
A storage water heater has sound, stud-anchored restraints in its upper and lower thirds. The lower strap is 2 inches above the gas controls. Moving that strap to 6 inches above the controls would keep it within the lower third and is permitted by the restraint instructions. How should the restraint installation be completed?
Correct answer: C - Move the lower strap to the permitted location 6 inches above the controls.
Several fixtures lose flow when used together. Gauges immediately before and after a whole-building cartridge filter both read 64 psi with all outlets closed. During simultaneous fixture use, the upstream gauge reads 61 psi and the downstream gauge reads 23 psi. Both gauges have been checked, and no valve lies between their taps. Where should the plumber direct the first repair?
Correct answer: C - Isolate and service the cartridge filter.
After a check valve is added at a home's water service, the water-heater relief pipe begins dripping during recovery. Pressure downstream of the regulator stays at 58 psi while the heater is off, then rises steadily during heating and falls when a faucet is opened. Stored-water temperature stays at 125 degrees F, matching the thermostat setting. No expansion tank is installed. Which defect best explains this pattern?
Correct answer: A - Unrelieved thermal expansion in the closed water system.
Before entry into a 4-foot-6-inch water-line trench, a competent person examines the soil and surrounding conditions and finds no indication of a potential cave-in. Spoils are 3 feet from the edge, utilities have been verified, and no other hazards are identified. The only ladder is 32 feet from the planned work position. Which correction is required?
Correct answer: A - Place a ladder within 25 feet of the work position.
On entering an occupied restaurant's mechanical room, a plumber notices a strong natural-gas odor and an unidentified hissing sound. The owner reaches for the exhaust-fan switch. What is the immediate priority?
Correct answer: A - Leave switches untouched, evacuate, and call for emergency help from a safe location.
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