Master Plumber Exam Plumbing Fixtures and Appliances 5 — Questions and Answers
Question 1: A food waste disposer (garbage disposal) installed under a kitchen sink must have its drain connection made to the:
- Tailpiece above the trap inlet (Correct answer)
- Downstream side of the P-trap
- Building drain directly
- Dishwasher drain line only
Correct answer: Tailpiece above the trap inlet
The disposer drain must connect to the sink tailpiece above the trap inlet so all waste passes through the trap before entering the drain system.
Question 2: Which material is prohibited for use as a lavatory drain tailpiece under most current US plumbing codes?
- ABS plastic
- PVC plastic
- Lead (Correct answer)
- Brass
Correct answer: Lead
Lead drain components for potable-water fixtures are prohibited by current codes and the Safe Drinking Water Act due to the risk of lead leaching.
Question 3: An emergency eyewash station in a laboratory must be located within how many seconds of travel from the hazard area?
- 5 seconds
- 10 seconds (Correct answer)
- 15 seconds
- 30 seconds
Correct answer: 10 seconds
ANSI Z358.1 requires emergency eyewash and shower stations to be accessible within 10 seconds (approximately 55 feet) of the hazard.
Question 4: A thermostatic mixing valve differs from a pressure-balancing valve in that it:
- Only controls pressure fluctuations, not temperature
- Maintains a set outlet temperature regardless of both pressure and temperature fluctuations (Correct answer)
- Is only used for industrial applications
- Does not require a check valve on each inlet
Correct answer: Maintains a set outlet temperature regardless of both pressure and temperature fluctuations
Thermostatic mixing valves maintain a constant outlet temperature by compensating for both inlet pressure and temperature changes, providing more precise scald protection.
Question 5: What is the maximum flow rate in gallons per minute allowed for a lavatory faucet under the EPA WaterSense program?
- 1.0 gpm
- 1.5 gpm (Correct answer)
- 2.0 gpm
- 2.5 gpm
Correct answer: 1.5 gpm
EPA WaterSense-labeled lavatory faucets must have a maximum flow rate of 1.5 gpm at 60 psi, compared to the standard 2.2 gpm.
Question 6: A whirlpool bathtub's circulation pump must be positioned so that:
- It is above the water line to prevent flooding
- It is accessible for servicing without removing the tub (Correct answer)
- The pump discharge faces downward into the drain
- It shares the same GFCI circuit as the bathroom lighting
Correct answer: It is accessible for servicing without removing the tub
Plumbing and electrical codes require the whirlpool pump to be accessible for inspection, repair, and replacement without requiring fixture removal.
Question 7: When a water heater is installed in a garage, it must be elevated so the ignition source is a minimum of how many inches above the floor?
- 6 inches
- 12 inches
- 18 inches (Correct answer)
- 24 inches
Correct answer: 18 inches
Water heaters with an open-flame ignition source installed in garages must be elevated 18 inches above the floor to keep the ignition source above potential gasoline vapor accumulation.
Master Plumber Exam Plumbing Fixtures and Appliances 5
A food waste disposer (garbage disposal) installed under a kitchen sink must have its drain connection made to the: