the -ve of generator will be directelly connected with the -ve of home wiring ,,,,,,,,there is no harm if you connect either of generator wire to -ve , in my previous generator i do care for that but in my new generator i havent bother to look for that ,,,,,,,,i put a mark on 2 pin show with carries the generator out to home wiring so that i always put it back in the same direction ,,,,,,,,,,,,,,,,,,its batter you follow the polarity