Plug Type in Vietnam

In short Vietnam uses Type A, C and F sockets, running at 220 V and 50 Hz. Vietnamese sockets commonly accept flat American pins alongside round European ones, at 220 V. A US appliance fits without an adapter and is destroyed unless it is dual-voltage — the fit is the trap, because it removes the moment where you would have stopped to check. And here is the part that costs people money: sockets in Vietnam accept flat American pins at 220 V. A US appliance plugs in with no adapter at all, and unless its label reads 100–240 V it is destroyed the moment you switch on. The fit is the danger, because it removes the moment where you would have stopped to check. The distinction to hold on to is that a plug adapter and a voltage converter are different objects: the adapter changes the shape so the plug enters the socket and passes the local mains straight through, while the converter changes the voltage. Almost everything sold as a travel adapter is only the first, which is exactly why it cannot protect anything. Frequency — 50 Hz here — matters much less than people expect, because any device with a switch-mode power supply converts the incoming mains to DC immediately and ignores it. It affects mains-synchronous motors and old mechanical clocks, which run proportionally fast or slow, and very little else.