Dangers of Importing CAD into Revit

Importing and Linking CAD should be avoided. But why? And if it is unavoidable, how can I do it safely?
Here are some answers:

Potential Issus with Importing/Linking dwg (CAD) files into Revit

• Corrupt dwg
• Large file size and extraneous information
• Linked CAD can become unlinked but will still display. This can cause confusion as to what the latest file is.
• Possibility of someone exploding, causing up to 10,000 extra elements.
• Many AutoCAD layers and linetypes are brought in after an explode
• Size of CAD needs to be under 20miles in diameter. There can be items which are not part of the primary drawing that are very far away from 0.
• Visual clutter
• dwg files from programs like AutoCAD Architecture and Civil 3D may need special plugins to see all of the data.

More Issues...

What Can be Done

In AutoCAD:
Wblock only necessary information
Purge
Audit

In Revit:
Always link, don't import
Current View Only (for 2D dwgs)
Detailed explanation here for Survey drawings

Importing  and Linking CAD Best Practices part 1
Importing  and Linking CAD Best Practices part 2

Imported 3D AutoCAD not Sectioning