This box has got to go somehow. Any ideas. Lock nut is designed for no clearance to unthread. Even the box itself is impossible, for its rusted spinning nut and bolt. Then there’s the elbow (shown) cemented in. Like it was installed with the notion it may want to come alive and move about. An initial tortuous plan, at a time when technology was such that it offered an 8-fuse panel. Obviously a mechanic type was in front of it at one time.
i will try first locking on to rusted nut and bolt. With panel loose, bang on tight lock nut for a thread or two. Then bang a star tool into concrete.