Can you use a US appliance marked 100 - 240 V in a country with 240 V electricity without using a converter?

Answer 1

Some small appliances, such as electric shavers, etc., have been designed to run safely on different supply voltages and frequencies. If that is so, it would be stated on their rating plates. In many cases, where the power needed is low, such as (say) less than 30 Watts, a cheap and simple "International Travel Socket Adapter" is all that is needed to make such a 120 Volt appliance plug-in and work. Many international airports have shops selling such adapters.

Further information which may be useful to mention here but is not part of the answer to this question:

In general the answer has to be: "Not if it has been designed and wired to run only on the 60 Hz mains frequency system that is used in USA, Canada and elsewhere."

The mains frequency in Europe and other 230 Volt areas is 50 Hz (Cycles per second) compared to 60 Hz in US, Canada and other 120/240 Volt areas. Some 60 Hz appliances will work fine but others with simple motors will run too slow on the lower frequency of 50 Hz.

However the most important difference is in the way that the Neutral wire is connected in appliances designed to run on 240 Volt 60 Hz supplies: in addition to a safety "Ground" conductor there are 3 wires, a Neutral wired as a "central" common return conductor and two 120 Volt 60 Hz live "hot legs" which are wired in opposing phase to one another. When one hot leg is "+" (120 Volts positive) the other leg is "-" (120 Volts negative).

In 240 Volts 50 Hz appliances there are only 3 wires altogether, a "Ground" conductor, one single 240 volt "live" or "hot" wire and a Neutral wire connected as a return to the single "hot".

So there is a 240 Volt voltage difference between the "Neutral" and the "Hot" conductor in the 50 Hz system and only a 120 Volt voltage difference between the "Neutral" and the "Hot"conductors in the 60 Hz system. At the point where the "Neutral" gets connected to the "Ground" this difference will cause serious problems! That is why an appliance designed to be connected onto the 60 Hz system cannot be used safely on the 50 Hz system without first having proper technical modification work done.

A licensed electrician or electrical engineer would be able to consider whether or not a particular large appliance, that was manufactured to work on 60 Hz-only, could be modified safely to run at the lower 50 Hz frequency. However it won't usually be worth the expense of doing the work because it would be more cost-effective to buy (new or secondhand) an equivalent large appliance designed to work on 50 Hz.