I've run into the same issue when trying to offload excess power from an off-site steam turbines powered by a volcano.
3x steam turbines are connected via conductive wire to 2 power transformers (which then offload power to main grid). Even though the load never exceeds 2k (as the consumers are not capable of drawing more than that), the conductive wire get continuously overloaded. It appears as if 1kW transformers were drawing more than 1kW from their input at their full capacity. The overload is infinitesimal, showing a red 2kW, with displayed load value never exceeding the limit.
I had to work around this problem by lowering steam temperature to keep the output safely below the limit, at around ~1.9 kW. There are however no good reasons for this setup not to work. Not having this as an option, leaves the only viable power setup to have all generators connected to main power spine via heavy watt wires, which I hope was not the intention of game authors.
I know about battery flipper mechanics that are possible to achieve similar offsite generators, but relying on 'infinite charing power' seems to be much worse abuse of game mechanics. I would expect the transformers to protect not only their output, but also the input (when they are the only consumers).
I'm happy to include screenshots if that helps to address this issue.