Which copper tubing type is commonly used for residential water piping and ACR applications and is thinner than Type K?

• A. Type M
• B. Type H
• C. Type L
• D. Type K

Answer: (C)

Copper tube types are graded by wall thickness, which affects how much pressure they can safely carry and how durable they are in different applications. The thickest is built for underground or high-pressure service, the middle thickness provides a good balance of strength and cost, and the thinnest is cheapest but has a lower pressure rating. For residential water piping and most air conditioning/refrigeration (ACR) line sets, the middle-thickness tubing is the go-to choice because it handles typical house pressures reliably while keeping costs reasonable. It’s strong enough for daily use, yet thinner than the thickest type, so it’s easier to work with and less expensive than Type K. The thinnest and the thickest options have specific uses and limitations that aren’t as well-suited to standard home plumbing or common ACR installations. Thus, the tubing with the medium wall thickness is the common choice for these applications.