Benedikt A. Goebel, project manager for a Chicago area contractor, found this unique installation while completing an office building renovation in the Chicago area. While the plumber was excavating for new risers, he came across some electrical feeders in terra cotta "conduit." Believe it or not, someone (hopefully a long time ago) pulled not one, not two, but three different feeders that ranged in size from 100A to 225A through the existing drain system. At the time these feeders were found, they were hot and supplying a well pump and some mechanical equipment in the building. Eventually the feeders were relocated and installed per current NEC requirements.
This drain pipe wasn’t designed to be used in this manner. Sec. 300.5(A) discusses minimum cover requirements for various electrical conduits permitted by Chapter 3. "Cover" is defined as the shortest distance measured between a point on the top surface of any direct-buried conductor, cable, conduit, or other raceway and the top surface of finished grade, concrete, or similar cover. Any direct-buried cable or conduit or other raceways is required to be installed to meet the minimum cover requirements of Table 300.5.
If these conductors were service cables, additional requirements come into play, such as those listed in 230.8, 230.32, and 230.49.