in regards to 'reversing diode' for AC...... does not exist. The only gadget that can make a reverse connection 'good' is an isolation transformer. All the LEDs and little lights show what is wrong with the shore connection, they do not rectify the issue. (pardon the pun, was not intentional).
Here is a diagram that can show you what is wrong with the power connections (at the dock
or at home), borrowed from https://theorycircuit.com/phase-neut...rcuit-diagram/
Four Red colour LEDs are used here, and resistors are 56KΩ / 1W.
LED1 is connected between Phase and Earth through Resistor.(here you can connect LED in any polarity).
LED2 is connected between Phase and Neutral.
LED3 is connected between Earth and Neutral.
These three LEDs will show the condition of AC power supply.
LED1 LED2 LED3 LED4 Status
ON ON OFF - Phase Neutral Earth wired correctly
OFF ON ON - Wrong Polarity of Phase/Neutral
ON ON ON - Open Earth or Neutral
- - - ON Blown fuse
LED 4 connected parallel to the fuse and it glows when fuse blown and appliance being connected the power source.
Another word for 'Phase' is 'Active'.
Note, if you were to built something like this, be aware that 220-240 volt is dangerous and can kill.