Comingling of plastic pipe shall not be allowed unless approved male or female adapters or other ______ fittings that have been approved.

• A. Transition
• B. Compression
• C. Elbow
• D. Coupling

Answer: (A)

Connecting plastic pipe to other materials requires fittings that can bridge the differences between material types and sizes and that are approved for this use. These are transition fittings. They include approved male or female adapters and other fittings designed to make a safe, code-approved change from plastic to another material (or to a different size). Elbows and couplings are for changing direction or joining like materials, and while compression fittings are common, they don’t specifically address transitioning between different materials. So transition fittings are the appropriate choice.