What are the regulatory PCB limits in transformer oil?

Many regulations classify equipment based on PCB concentration in the oil. In US rules, “non PCB” is generally below 50 ppm, “PCB contaminated” is 50 to 500 ppm, and “PCB transformer” is typically 500 ppm or higher, which triggers strict marking, handling, and disposal controls. Local requirements vary, so operators verify their jurisdiction and documented lab results before decommissioning decisions.