306A National Plumbing Code of Canada 2 — Questions and Answers
Question 1: What is the maximum number of fixture units that can be connected to a 2-inch horizontal branch according to the Code?
- 4
- 6 (Correct answer)
- 8
- 12
Correct answer: 6
The Code allows a maximum of 6 fixture units on a 2-inch horizontal branch to prevent overloading and ensure proper drainage.
Question 2: According to the National Plumbing Code of Canada, what type of fitting must be used to change direction in a horizontal drainage pipe?
- Short-radius elbow
- Long-sweep fitting or combination wye (Correct answer)
- Standard 90-degree elbow
- Any available fitting
Correct answer: Long-sweep fitting or combination wye
Long-sweep fittings or combination wye fittings are required for direction changes in horizontal drainage to maintain flow velocity and reduce the risk of blockage.
Question 3: What is the minimum size of a vent stack serving a building with more than 10 fixture units?
- 1¼ inch
- 1½ inch
- 2 inch (Correct answer)
- 3 inch
Correct answer: 2 inch
A vent stack serving more than 10 fixture units must be at least 2 inches in diameter to provide adequate air circulation for the drainage system.
Question 4: How far above the flood level rim of the highest fixture must a vent terminate according to the Code?
- 50 mm
- 100 mm
- 150 mm (Correct answer)
- 300 mm
Correct answer: 150 mm
The vent must terminate at least 150 mm above the flood level rim of the highest served fixture to prevent waste water from entering the vent system during backup conditions.
Question 5: Under what conditions does the Code permit the use of an air admittance valve (AAV)?
- AAVs are prohibited under all circumstances
- Only when approved by the local authority having jurisdiction (Correct answer)
- Anywhere a traditional vent would be required
- Only in single-family dwellings
Correct answer: Only when approved by the local authority having jurisdiction
The National Plumbing Code of Canada permits air admittance valves only when approved by the authority having jurisdiction, as they are considered an alternative venting method.
Question 6: What is the minimum pipe size for a building sewer according to the National Plumbing Code of Canada?
- 3 inch
- 4 inch (Correct answer)
- 6 inch
- 8 inch
Correct answer: 4 inch
The Code requires a minimum 4-inch building sewer to handle the combined flow from all building fixtures and to maintain self-cleansing velocity.
306A National Plumbing Code of Canada 2
What is the maximum number of fixture units that can be connected to a 2-inch horizontal branch according to the Code?