EDIS allows users to upload and share most documents, including building and electrical drawings. In order to view drawings an Autocad viewer is required. You need to download this Free viewer and Install it before you can view CAD drawings on EDIS.

To download the Free viewer go to : http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=4424149 Save the file to your desktop and once it has downloaded, you need to install the viewer by double-clicking on the icon

More about the Drawing Viewer.
EDIS enables AutoCAD drawings in the DWF format to be viewed. The DWF file format is purpose-built to share complex design information while maintaining its integrity with file sizes that are often 1/10 the size of other file formats. The AutoDesk DWF Viewer provides a free solution for users to view and print 2D and 3D designs published to DWF format from