PVC breaker distribution boxes are robust electrical enclosures designed to house and protect circuit breakers and associated electrical components. Each. What is the difference between thermoset and thermoplastic materials? You can find distribution boxes made from various distribution box materials such as steel, aluminum, PVC, polycarbonate, high-density polyethylene, and thermoset plastics like SMC. Think of them as traffic controllers for power—they direct energy where it needs to go while protecting against overloads or. Distribution boxes are commonly used in residential and commercial electrical systems.