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Plumber Red Seal · Question

A plumber is installing drainage for a dishwasher and a kitchen sink in a residential dwelling. The kitchen sink has a double basin. According to the National Plumbing Code of Canada, what minimum trap arm size is required to serve these fixtures if they are connected to a single trap?

The National Plumbing Code of Canada (NPC) dictates that a kitchen sink with a double basin and a dishwasher typically requires a minimum 51 mm (2 inch) trap ar

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Question: A plumber is installing drainage for a dishwasher and a kitchen sink in a residential dwelling. The kitchen sink has a double basin. According to the National Plumbing Code of Canada, what minimum trap arm size is required to serve these fixtures if they are connected to a single trap?

Answer options:

  • 38 mm (1 1/2 inch) ✅ 51 mm (2 inch)
  • 64 mm (2 1/2 inch)
  • 76 mm (3 inch)

Correct answer: 51 mm (2 inch)

Explanation: The National Plumbing Code of Canada (NPC) dictates that a kitchen sink with a double basin and a dishwasher typically requires a minimum 51 mm (2 inch) trap arm. A 38 mm (1 1/2 inch) trap arm is insufficient for the combined drainage load of these fixtures.

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