Users reported that commands like "ADD CABLE TRAY" in AutoCAD MEP fail to work from the Tool Palette. An "unknown command 'DBOX' Press F1 for help. Right click the tool (in property palette) and click "Properties". When you create a cable tray in AutoCAD MEP and choose "Ladder" as subtype, the tray properties can be configured to show ladder lines in 2D views as annotational representation. But in 3D views it remains as a U-channel or a boxed channel. Screenshot: - AutoCAD MEP, cable tray properties dialog on. Autodesk does not warrant, either expressly or implied, the accuracy, reliability or completeness of the information translated by the machine translation service and will not be liable for damages or losses caused by the trust placed in the translation service. Translate 04-10-2009 08:21 AM. Electrical cable tray layout is a ready-to-use CAD block perfect for building services, industrial setups, and electrical projects. This collection includes installation details for ladder trays, perforated trays, solid-bottom trays, and wire mesh trays, along with. Free CAD and BIM blocks library - content for AutoCAD, AutoCAD LT, Revit, Inventor, Fusion 360 and other 2D and 3D CAD applications by Autodesk. CAD blocks and files can be downloaded in the formats DWG, RFA, IPT, F3D.