What is the maximum developed length of a 1.5-inch trap arm for a lavatory sink?

Question: What is the maximum developed length of a 1.5-inch trap arm for a lavatory sink?

Answer options:

• 1.2 m (4 ft)
• 1.5 m (5 ft) ✅ 1.8 m (6 ft)
• 2.4 m (8 ft)

Correct answer: 1.8 m (6 ft)

Explanation: The National Plumbing Code limits the developed length of a 1.5-inch trap arm to 1.8 m (6 ft) to ensure proper drainage and prevent self-siphonage of the trap seal.