Supply line is usually no smaller than what diameter?

The correct answer of a supply line being usually no smaller than 3 inches in diameter is based on standard practices in firefighting operations. A supply line is crucial for transporting water from a hydrant or another source to the fire scene, and it needs to have sufficient diameter to ensure an adequate flow rate.

A 3-inch diameter hose provides the necessary capacity to quickly deliver large volumes of water, which is essential during firefighting operations. Using a hose smaller than this can lead to inadequate supply for the firefighting efforts, as it may not be able to sustain the water pressure required for effective fire suppression.

The choices of 2 inches, 4 inches, and 5 inches do not align with the common practice for supply lines. While 2-inch hoses may be used for certain applications, they typically do not meet the requirement for a primary supply line in fire service operations. On the other hand, while a 4-inch and 5-inch supply lines are indeed used and are capable of delivering even more water, they are generally designed for specific heavy-duty scenarios or to feed multiple smaller lines rather than serving as the standard supply line diameter. Thus, the 3-inch diameter strikes a balanced choice for a primary supply line in firefighting contexts