How many fittings are involved in a center to center measurement?

The correct understanding of center-to-center measurements in plumbing involves two fittings. This measurement is commonly used to determine the distance between the centers of two connected fittings, such as in a piping system where two pipes connect through fittings like elbows or tees.

When measuring from the center point of one fitting to the center point of another, it’s crucial to recognize that each fitting contributes to the overall length being measured. Therefore, if you're calculating from one fitting to another, you’re essentially involving both fittings in that measurement, which is why the answer is two.

Understanding this concept is vital for accurate installations and ensuring that systems function properly without excess strain or improper alignment.