When installing no-hub couplings underground the no-hub coupling shall have a minimum of ________________ bands.

The requirement for no-hub couplings installed underground to have a minimum of four bands is based on the need for enhanced structural integrity and secure connections in plumbing systems. Four bands provide sufficient surface area and support for the coupling to ensure that it can withstand soil pressure, movement, and any potential differential settling that may occur underground.

In underground plumbing, the environment can be challenging due to moisture, soil variability, and ground movement, all of which can affect the stability of the plumbing connections. With four bands, the no-hub coupling is secured enough to resist separation, leaks, and potential failure over time, thus contributing to the overall reliability of the plumbing system.

The code stipulates this minimum number of bands to mitigate the risks associated with underground installations, emphasizing the importance of proper technique and material standards in plumbing practices.