All copper oil supply and return lines must be encased in what type of conduit?

The correct answer is that all copper oil supply and return lines must be encased in non-metallic liquid tight conduit. This requirement is primarily based on the need to protect the copper lines from damage caused by moisture, corrosion, and physical impacts. Non-metallic liquid tight conduit serves this purpose effectively because it offers both flexibility and resistance to various environmental factors.

Using non-metallic conduit also prevents potential electrical issues that can arise from metal conduits. Since copper is a conductive material, encasing it in a non-conductive medium like non-metallic conduit minimizes the risk of electrical shorts or grounding issues. Furthermore, this type of conduit is designed to be watertight, which is crucial in preventing any leakage that could contaminate the surrounding area or affect the operation of the heating or oil system.

While other types of conduits such as metallic conduit and flexible conduit have their own uses, they do not provide the same level of protection from corrosion and moisture that non-metallic liquid tight conduit offers, making it the most suitable choice for encapsulating copper oil supply and return lines.