I entered into a business transaction of the sort "you buy two
compressors and whatever else you find in the building, including
wiring, for $500".

The building, a former car body shop, is to be demolished next week.

Today we took out a lot of wiring, including one inch copper mains
cables, and a 15 HP I-R T30 compressor and a 5 HP quincy compressor.

Pulled a lot of cable from the walls also. The cables pull, once we
released their "other ends" in their respective panels.

But here's a problem: one of the cables, I am guessing 2-0 gauge, four
conductors, is going into the conduit in the floor concrete.

We cannot find the panel that they are going to and we cannot pull
them out, as they are attached on their other ends. I am beginning to
think that perhaps they are extremely long and valuable.

Is there some low-tech way to trace where that conduit is going?