yes.
120V appliance will not work on 220V. Use an instrument transformer or voltage regulator to adjust the high voltage to the desired level.
No. Attempting to run an appliance on insufficient voltage can cause damage to the appliance and can be dangerous. Call an electrician and get him to install a 220v plug
A high voltage will certainly damage a low voltage appliance and perhaps set fire to other things nearby.
The fourth prong grounds the body of the appliance. You can attach it to the frame or simply ignore it.
normally, appliance are built in 110v or 220v, applied in 100-140v and 200-240v. if your 250v appliance is common home appliance equipment, then 220volt is ok, i think. otherwise, you should ask the vendor for special power supply.
The voltage and frequency range depends on the individual appliance, but each appliance should have a small plaque on it near where the power cord enters, telling you the working range.
No. 220V adaptor can't control the output voltage, 110V appliance will be fry. Use instrument transformer or voltage regulator instead.
You will have trouble plugging a 220 volt appliance into a 110 volt outlet because both have different polarities for the plug and receptacle that make it impossible for that action to happen.Altering the plug isn't too good of an idea, as the voltage demand of the appliance would be too heavy for the wiring.
The voltage isn't a problem, you can run 220 from your house and use that to run a European appliance, the problem is whether the appliance is dependant on line HZ. European is 50HZ and US is 60HZ. If the appliance specifies 220/50HZ, it will probably give you trouble here. If it says 220V/50 or 60HZ
You need to convert the voltage if your appliance requires less voltage than you power supply. example: appliances is 110V and power supply is 220V.
The energy consumption for the same appliance the power consumption in watts would be the same watts = volts X amps. In general if an appliance requires 10 Amps @ 110V then it would only require 5 amps @ 220V In general in an a North American house the appliances that run on 220V are on 220 because they would pull too much power to be logically wired on 110V. So they do pull more power than most 110V appliances.
Basically - you're stumped !... If there are explicit instructions with the appliance that you do not use a converter - there is a legitimate reason for NOT doing so ! Your only option is to purchase an equivalent appliance in the country you're going to ! One of the reasons they are telling you you are not to use a converter - is that most US converters are only 2-pin. The appliance you have may need an earth connection to maintain safety.