The company I work for manufacturers pre-fab steel shelters for various utilities and recently we had a request I've never dealt with before.....two 240vac 1 phase, AC panels, on exact opposite walls (400amp MB in each), with one feeding the other through feedthru lugs. The customer doesn't want to use the cable tray to get across the room, but rather go through the floor. It's a steel floor, roughly 10" deep (C-channel) and insulated with 1/4" steel plates on top for the finished floor. The run would be apprx. 15' under floor. Originally, we planned on setting PVC in an open channel, before installing the floor,90 degree elbows coming out of the floor below each panel. I say originally because it was going to be 225amps. Now with the 400amp requirement, we're looking at parallel runs of 4/0 and a larger conduit. My question is, can (6) 4/0 wires be bundled up and set to lay loose in the channel in the floor, with either a PVC pipe or wireway coming down from the panels to the 1/4" steel floor for entry into them? (I'd put a wireway adapter or a coupling on the underside of the deck plate to protect the wires as they came up through the floor, we're just trying to avoid an elbow since a 3" pipe would have a rather large radius coming up from the floor if we ran continuous pipe). Sorry for the novel, those still awake, I'd appreciate any suggestions! Thanks!