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Plumber Red Seal · Question

A plumber is sizing the water service line for a new single-family home. The total load is 25 WSFU and the run from the main is 20 meters. Given typical friction loss tables in the NPC, what is the *minimum* acceptable service pipe size?

While detailed calculations are required, a 1/2-inch pipe would have excessive friction loss for a whole house load. A 3/4-inch service is the standard minimum

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Question: A plumber is sizing the water service line for a new single-family home. The total load is 25 WSFU and the run from the main is 20 meters. Given typical friction loss tables in the NPC, what is the minimum acceptable service pipe size?

Answer options:

  • 1/2 inch ✅ 3/4 inch
  • 1 1/4 inch
  • 1 1/2 inch

Correct answer: 3/4 inch

Explanation: While detailed calculations are required, a 1/2-inch pipe would have excessive friction loss for a whole house load. A 3/4-inch service is the standard minimum for most single-family dwellings to ensure adequate pressure and flow, especially for a load of 25 WSFU.

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