At one of the McCormick Place buildings in Chicago the EC got the brilliant idea to lay EMT in the troughs of the metal floor pan before the concrete was poured. It seemed quicker and cheaper than using chairs to suspend the conduits.
That worked out fine until the Carpenters started installing the suspended ceilings on the floor below...using power fasteners to attach their support wires to the deck.
They hit a LOT of the conduits that then had to be replaced with different conduit which now had to be installed overhead (20' ceilings) to power the receptacles and other loads.
Unfortunately for the EC the rework couldn't be claimed as an extra.
