How to reproduce:
1) Load savegame: 2) Try to place substation: Happens also when constructing from blueprint.
Vanilla game, no mods, Steam (Windows x64), Version 0.15.33
Tried to create a smaller testcase for this, but failed

It seems to me that there is something broken with the substation above (see picture).
Edit: The reason was just that the maximum number of wire connections (5) for the substation above was already reached.