Another angle to ponder is whether or not the original EC has rights to his electrical design. There may be some proprietary rights there??? If the owner has paid him for the plans and his time, would the owner now have full rights to the documents?
Let's say the new EC may be stepping on the original EC's toes by using his plans and bidding against him.
If there was no written agreement regarding this issue. Who would you think would be more likely to prevail in the event of a dispute?