Journeyman Plumbers Plumbing Fixtures and Appliances Questions and Answers — Questions and Answers
Question 1: A plumber is installing a gas-fired water heater with a bottom ignition source in a residential garage. According to most plumbing codes, what is the minimum required elevation of the ignition source above the garage floor?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
To prevent the ignition of flammable vapors (such as gasoline or solvent fumes) that are heavier than air and can accumulate near the floor, plumbing and mechanical codes require the ignition source of fuel-fired appliances to be elevated. The standard minimum height is 18 inches above the floor in locations like a garage.
Question 2: Which of the following is a code-compliant method for connecting a domestic dishwasher's drainage hose to the sanitary drainage system to prevent backflow?
- A direct connection to the garbage disposal's inlet.
- A P-trap installed exclusively for the dishwasher.
- An approved air gap fitting installed on the countertop. (Correct answer)
- A simple loop in the drain hose below the sink rim.
Correct answer: An approved air gap fitting installed on the countertop.
Most plumbing codes mandate that a domestic dishwasher must discharge through an approved air gap fitting to prevent contaminated water from the sink or drainage system from siphoning back into the dishwasher. The air gap provides a physical separation, making it a reliable backflow prevention method. While some jurisdictions may allow a high loop as an alternative, the air gap is the specifically listed and most protective device.
Question 3: A journeyman plumber is installing fixtures in an ADA-compliant public restroom. What is the required height range for the toilet seat above the finished floor?
- 14 to 16 inches
- 17 to 19 inches (Correct answer)
- 20 to 22 inches
- 23 to 25 inches
Correct answer: 17 to 19 inches
The Americans with Disabilities Act (ADA) standards require that the top of the toilet seat in an accessible restroom be between 17 and 19 inches above the finished floor. This height makes it easier for individuals with mobility impairments, particularly those transferring from a wheelchair, to use the fixture.
Question 4: A Temperature and Pressure (T&P) relief valve on a water heater must have its temperature-sensing element installed in a specific location to function correctly. Where must this element be located?
- In the cold water inlet pipe.
- At the midpoint of the water heater tank.
- Within the bottom 6 inches of the tank.
- Within the top 6 inches of the tank. (Correct answer)
Correct answer: Within the top 6 inches of the tank.
The T&P valve's temperature-sensing element must be immersed in the hottest water of the tank to provide accurate protection against excessive temperatures. The hottest water is always in the top 6 inches of a storage-type water heater. Installing it elsewhere could create a thermal lag, delaying its activation and creating a safety hazard.
Question 5: In a commercial building, a floor drain is located in a mechanical room that is rarely used, making the trap seal subject to evaporation. Which device is required to maintain the trap seal?
- A check valve
- A vacuum breaker
- A trap primer (Correct answer)
- An air admittance valve
Correct answer: A trap primer
A trap primer is a device that automatically supplies a small amount of water to a trap that is subject to losing its seal through evaporation, such as an infrequently used floor drain. This maintains the water seal, which is necessary to prevent sewer gases from entering the building.
Question 6: When installing a lavatory to meet ADA accessibility standards, which of the following requirements for the pipes under the sink is correct?
- Pipes must be made of chrome-plated brass.
- A mechanical vent must be installed directly under the sink.
- Pipes must be insulated or configured to protect against contact. (Correct answer)
- Pipes must be concealed within a cabinet.
Correct answer: Pipes must be insulated or configured to protect against contact.
To comply with ADA standards, the hot water and drain pipes under a lavatory must be insulated or otherwise configured to protect against contact. This prevents individuals in wheelchairs, whose legs may touch the piping, from being burned or injured by sharp or abrasive surfaces.
