Master Plumber Plumbing Codes and Regulations Questions and Answers

Question 1

According to most model plumbing codes, what is the primary method required to protect the potable water supply at individual shower and tub/shower combination valves against scalding and thermal shock?

Accepted Answer

Installation of individual control valves of the pressure-balance, thermostatic, or combination type.

Answer

Installation of a tempering tank upstream of the water heater.

Answer

Use of oversized PEX tubing to reduce pressure fluctuations.

Answer

A mandatory minimum distance of 10 feet between the water heater and the fixture.

Question 2

A master plumber is overseeing a new commercial installation. According to the IPC, if an individual vent has a total developed length of 45 feet, what specific code provision must be followed regarding its size?

Accepted Answer

The vent must be increased by one nominal pipe size for its entire length.

Answer

The vent size must be at least two-thirds the diameter of the drain it serves.

Answer

The vent can be the standard size, which is one-half the diameter of the drain served.

Answer

A secondary parallel vent must be installed to supplement the primary vent.

Question 3

When installing a horizontal building drain that is 4 inches in diameter, what is the minimum required spacing for cleanouts according to the IPC?

Accepted Answer

Every 100 feet

Answer

Every 50 feet

Answer

Every 75 feet

Answer

Every 150 feet

Question 4

A plumber is installing an individual, branch-type Air Admittance Valve (AAV) for a lavatory sink in a renovated bathroom. Which of the following installation requirements is correct according to the IPC?

Accepted Answer

The AAV must be located a minimum of 4 inches above the horizontal branch drain or fixture drain being vented.

Answer

The AAV must be located a minimum of 2 inches below the horizontal branch drain.

Answer

The AAV must be installed outdoors and protected from frost.

Answer

The AAV can serve as the only vent for the entire building's drainage system.

Question 5

A multi-story building has a drainage stack with seven branch intervals. Which of the following is required by the International Plumbing Code?

Accepted Answer

A vent stack is required.

Answer

The stack must be made of cast iron pipe only.

Answer

The stack size must be increased by one pipe size at the fifth branch interval.

Answer

A cleanout is required at every branch interval.

Question 6

Which of the following scenarios necessitates the installation of a backflow prevention device or assembly to protect the potable water system?

Accepted Answer

A hose bibb to which a garden hose and chemical sprayer could be attached.

Answer

A gravity-fed water dispenser connected to a bottled water jug.

Answer

A standard residential lavatory faucet with an spout ending 8 inches above the flood level rim.

Answer

The connection between a water meter and the service line from the public main.