The project we were working on was the replacement of a damaged secondary bushing in an induction furnace transformer with a throat connected fused disconnect switch. The switch was our lock out and grounding point for the primary of the transformer. Upon opening the door on the unit, a distinct smell of ozone was present. At first, this was ignored as it was thought to have come from a load break operation. As the day progressed, working around the unit, the smell was still present. As the line side of the switch was tied to the plant main, it was not easy to isolate. In discussion with our plant contact, it was decided to investigate further and an outage was arranged. Below is what we found.