A plumber is installing a series of floor drains in a warehouse. According to the NPC, these floor drains must be protected from freezing if they are located in an unheated area. What is the primary reason for this requirement?

Question: A plumber is installing a series of floor drains in a warehouse. According to the NPC, these floor drains must be protected from freezing if they are located in an unheated area. What is the primary reason for this requirement?

Answer options:

• To prevent damage to the drain fixture itself.
• To ensure the trap seal is not lost due to evaporation. ✅ To prevent expansion of frozen water from cracking the pipes and losing the trap seal.
• To allow faster drainage of waste water.

Correct answer: To prevent expansion of frozen water from cracking the pipes and losing the trap seal.

Explanation: The primary reason for protecting floor drains in unheated areas from freezing is to prevent the water in the trap seal from freezing. When water freezes, it expands, which can crack the trap or pipe, leading to a loss of the trap seal. A lost trap seal allows sewer gases to enter the occupied space, posing a health hazard. While freezing can damage the fixture, the critical issue is maintaining the trap seal. Evaporation is addressed by trap primers, and faster drainage is unrelated to freezing.