Abstract: This article briefly introduces the working principle of series electric heat tracing, draws the equivalent circuit of series electric heat tracing, lists the calculation formulas for series parallel circuits, and verifies them by combining with the on-site electric heat tracing fault situation, providing valuable experience for the electrical industry to search for grounding faults in series electric heat tracing. Based on the recent electric heat tracing fault phenomena in chemical plants, it summarizes and classifies them, and provides construction suggestions for electric heat tracing.