Not sure what size the power feeder is. I can tell you it is the standard heavy US 50A 220V yellow wire. We use this wire because the factory Amel black cable spectacularly caught fire in early 2013, about 10 feet away from the boat, one day when we were using almost 7KW on shore power.
Peregrinus anchors out a lot. In Florida, it routinely loaded up as follows during the first hour after it got to shore:
2 A/C units @ 900W e.a.
1 A/C unit @ 1200W
1 A/C water pump @? W
1 battery charger 30A = 840W
1 battery charger 100A = 2800W
That's 6,640 + the water pump. And that's assuming no power consumption from any outlets, and assuming the water heater is either off or already warm.
As mentioned above, "The inverter can be left ON or OFF at all times, if you wish, because it has an autoswitch". In other words, the Xantrex Prosine 1800watt 220volt 50hz inverter system 808-1800 detects if there is shore power available on the system and if there is, it simply passes it thru, even if it is 60Hz. This is why if 50Hz power is desired while on shore power on a 60Hz country, for, say, the espresso maker, one must "turn OFF the little yellow 32A breaker located on the side of the 230V AC panel."
Cheerio,
Peregrinus
El Rompido, Huelva