If I have a blueprint that has a power wire that happens to overlap an existing power wire it seems to place the new wire and still keep the old wire. As a result the same wire will occupy the same space and then the game bugs a bit and neither wire will act like it is connected to the rest of the circuit. The only way I have found to fix this after the fact is to manually select both wires and click the deconstruct button. If I use the deconstruct tool the game will deconstruct just one of the two and then won't recognize the second wire unless it is manually selected.