Just came back from Trat, no requirements for the ferry.
What I hear from hotels, some seem to ask for a negative test, most don't, and many are closed.
Looks like the neutral is switched instead of the phase. Switch the 2 wires and see what happens.
Explanation: if the neutral is switched and it's dry, the current does not find a way to the graound. When it's wet, the water will conduct the current to the ground. Worsens with salt and dirt or dust.