There are two ways to determine the block name of an existing symbol:
METHOD A
Insert the symbol from the AutoCAD Electrical toolset icon menu.
Use the AutoCAD LIST command to display the block name.
Add the appropriate library path as a prefix to this block name to obtain the path to the ".dwg" file of the symbol. The default library path is \Users\Public\Documents\Autodesk\Acade {version}\libs\{library}\ .