All properly designed marine battery chargers and inverters will use an isolation transformer to do the voltage step up/down. This keeps the DC Negative separate from the AC Neutral.
A connection between AC Neutral and DC Negative from poorly designed equipment is potential corrosion problem on an Amel, and a serious disaster waiting to happen on any boat. If it is connected to a shore power plug that has reverse polarity (Hot and Neutral swapped) the entire DC system is now charged with AC Power. I am not sure what would go wrong first, but it wouldn't be pretty! If you haven't come across a marina with wiring like this, keep traveling, you eventually will!
It is always good to have to think about these things carefully enough to write them out...
North Bimini, Bahamas