OI-233814 Grid overloaded but only connected to one transformer. Shows higher grid capacity than expected.

You're using the wrong bridge on the heavy watt wires.
 

No it is not the brigde. The standard bridge is still working with heavy watt wire. I have removed and placed again some tiles of heavy watt wire and then the overload problem stopped. And my screenshot shows more my confusion with the UI. 2040 is the actually the maximum consumer load, not the producer input. 

consider it solved.

@SchlauFuchs,  Sounds like a phantom connection. I had concocted this elaborate post about a hidden wire bridge but it seems you've solved it already. Here's some graffiti...