Journeyman Plumbers Exam Gas Piping and Venting 4 — Questions and Answers
Question 1: When installing a gas range in a kitchen, the flexible connector used must NOT exceed what length?
- 2 feet
- 3 feet
- 6 feet (Correct answer)
- 10 feet
Correct answer: 6 feet
Appliance connectors for gas ranges and similar equipment must not exceed 6 feet in length per NFPA 54.
Question 2: Natural gas has a specific gravity approximately:
- Heavier than air (specific gravity greater than 1.0)
- Same weight as air (specific gravity of 1.0)
- Lighter than air (specific gravity less than 1.0) (Correct answer)
- Twice as heavy as air
Correct answer: Lighter than air (specific gravity less than 1.0)
Natural gas (primarily methane) has a specific gravity of about 0.6, making it lighter than air so it rises and dissipates upward.
Question 3: A gas vent that serves only one appliance and terminates through an exterior wall using an approved through-the-wall kit is known as:
- A Type B vent
- A direct-vent (sealed combustion) system (Correct answer)
- A power-vented system
- A combination vent
Correct answer: A direct-vent (sealed combustion) system
A direct-vent (sealed combustion) appliance draws combustion air from outside and exhausts directly through the wall, using a coaxial or two-pipe assembly.
Question 4: Which of the following conditions ALWAYS requires a licensed plumber or gas fitter to obtain a permit before work begins?
- Replacing an existing gas appliance connector (same size)
- Installing new gas piping or extending an existing gas line (Correct answer)
- Lighting a pilot light
- Cleaning a burner orifice
Correct answer: Installing new gas piping or extending an existing gas line
Any new gas piping installation or extension of an existing gas system requires a permit to ensure the work is inspected and meets code.
Question 5: What is the minimum horizontal distance a gas meter must be located from an electrical meter or service panel?
- 1 foot
- 3 feet (Correct answer)
- 5 feet
- 10 feet
Correct answer: 3 feet
Gas meters must be installed at least 3 feet horizontally from electrical meters and service equipment to reduce ignition risk.
Question 6: A plumber notices a gas odor while working in a building. The FIRST action should be:
- Attempt to find and tighten the leaking fitting
- Turn on ventilation fans to dilute the gas
- Evacuate the building and call the gas company from outside (Correct answer)
- Turn off the main electrical panel to prevent sparks
Correct answer: Evacuate the building and call the gas company from outside
Evacuating and calling the utility from a safe location is the correct first response — do not operate switches or fans that could ignite accumulated gas.
Question 7: A gas dryer vent (exhaust) must be made of:
- Flexible plastic duct
- Rigid or semi-rigid metal duct (Correct answer)
- PVC pipe
- Type B gas vent
Correct answer: Rigid or semi-rigid metal duct
Gas dryer exhaust must use rigid or semi-rigid metal duct — not plastic — because of the heat and potential for fire.
