Originally Posted by
B747-437B
There is no specific line for non-EU in Frankfurt in my recollection. The lines are for only EU/EEA/Switz. passport holders, and for ALL PASSPORTS (which includes both EU and non-EU). Therefore, the ALL PASSPORTS line should be used if you want to clear passport control together.
There are specific lines for non-EU, and those are indeed the "All Passports" lines which the OP should use.
I've used my US passport in the EU/EEA/CH line on some Schengen exits (as a desperate measure to make my flight, when having an EU country's resident card to present) or when the EU/EEA/CH lines were empty and/or they forgot to change the sign to an All Passports line, but the odds of being rejected or getting dirty looks is rather high if there is any crowd whatsoever behind me in line.
Technically the EU/EEA/CH line is actually used by some Europeans other than just those of the EU/EEA/CH. It is allowed, for example, to those Danish-issued passport users who are not holders of a passport issued to people of the EU/EEA/CH -- those being some Faroe Islanders, passports of which I've seen at CPH and KEF more than elsewhere (since those are the primary flight countries for people from non-EU/non-EEA/non-EFTA Faroese).