What is an acceptable use of dielectrics in plumbing?

The use of dielectrics in plumbing is primarily to prevent corrosion when joining dissimilar metals. When two different metals come into contact in the presence of moisture, galvanic corrosion can occur, which damages the metal surfaces. Dielectric fittings or unions act as a barrier between the two metals, effectively interrupting the electrical path that facilitates corrosion. This protection helps to prolong the lifespan of plumbing systems by ensuring that connections between different types of metals do not degrade over time.

Other options may have their applications in plumbing, but they do not pertain to the unique protective role that dielectrics serve between dissimilar metals.