If you want to match the file AND folder in the same string you can do it using the Containing Text field. If you have the option Include folder path in content search then Line zero of the file will effectively include the full path to the file.

You can then limit the search to just line zero using the LINES operator, e.g. to find .doc files that are directly below a folder called 'electrical' you could use something like:
File name: *.doc
Containing Text: LINES:0 REGEX "electrical\\[^\\]+\.doc"
Look In: C:\
To speed up the search switch OFF Office/PDF Documents enhanced file searching in the Options tab unless you actually want to also search the contents of the DOC files.
Scripting alternative
In the Sample Scripts folder there is a file called path_regexp.js
. Change the line:
bIsValid = regExp.test( strPath );
to
bIsValid = regExp.test( strPath + strFileName );
And this will compare the supplied regex to the whole path.
More information:
The 'normal' way to achieve this would be something like:
File name: *.doc
Containing Text:
Look In: C:\;+electrical
but this would find .DOC files where the term 'electrical' was anywhere in the path, not just the .DOC files parent folder.