Conduit Routing Through a Congested Corridor With Cable Tray
A hospital corridor 8 feet wide by 9 feet high carries a 24-inch cable tray along the ceiling, two 4-inch conduits, and a 6-inch medical gas line. Your electrical model routes 14 homerun conduits from panels on the corridor's south wall to a north-side equipment room. The mechanical model has a 30-inch duct crossing the corridor at 8 feet above finished floor, and the structural model has a beam at 8'-6". The current routing shows three conduits passing through the duct and two through the beam. The contractor wants to use the cable tray for the homeruns to reduce conduit count.
1. Evaluate the routing conflicts and explain how you would use Revit's tools to identify and resolve them before issuing the model.
Read the worked answer
The conflicts are hard clashes: three conduits intersect the duct and two intersect the structural beam. These must be resolved before issue because they are constructability failures, not coordination preferences.
Use Interference Check between the electrical model and the linked mechanical and structural models, scoped to the conduit and cable tray categories, to produce a complete clash list rather than relying on visual inspection. Supplement with a 3D section view of the corridor and Navisworks or Revit clash detection if the federated model is available.
Resolution options: reroute conduits below the duct with adequate clearance, consolidate homeruns into the cable tray where code and fill allow, or coordinate a penetration with the structural engineer for the beam (never cut a beam without approval). The medical gas line requires separation per code, so maintain the required clearance and do not route conduit through the same sleeve.
After rerouting, re-run the interference check and document the resolution in the coordination log with the date and reviewer.
2. The contractor proposes moving homeruns into the cable tray. What would you verify before agreeing, and how would you model it?
Read the worked answer
Verify cable tray fill and ampacity. Cable tray used for power conductors has fill and derating rules; a 24-inch tray carrying 14 homerun circuits may exceed allowable fill or require derating that changes conductor sizing. Confirm the tray's intended use (power vs. communications) and whether barriers are required.
Verify code separation: power and communications in the same tray require separation or barriers, and medical gas proximity rules still apply.
Verify the tray route actually reaches the equipment room and that drops from tray to panels are modeled.
Modeling approach: model the tray as a cable tray element with the correct width and height, then model homerun conduits from the panel to a point above the tray, and represent the transition. Use conduit runs with the correct bend radius. Keep the tray and conduits on separate worksets for coordination. Update the panel schedule and conduit schedule to reflect the changed routing, and record the design change in the calculation and drawing notes.