Residential electrical outlets in some countries including the United States use 110-120 volts of electricity, and accept very specific shaped plugs. Many other countries including Nepal use other voltages, 220-240 volts to power their appliances, as well different plugs. If you try to plug an American appliance such as a shaver or hairdryer into an outlet of a different voltage, you may destroy the appliance and cause yourself injury. There are few things you should know about other countries (here Nepal) before you travel. 
 

• Nepal’s Electricity is 220-240 Volts and 50 HZ (some countries like U.S and Canada are 110-120 volts/60 HZ).
• In Nepal electric Plugs are of two or three round prongs, but not flat prongs as found in use in the United States or in other countries.
• If your appliance's plug doesn't match the shape of these sockets, you will need a travel plug adapter in order to plug in. Travel plug adapters simply change the shape of your appliance's plug to match whatever type of socket you need to plug into. If it's crucial to be able to plug in no matter what, bring an adapter for both types.
• If you are planning on taking a hair dryer, electric shaver, curling iron, laptop computer or other electrical devices on your travels, in these cases, you will need to obtain either a voltage adapter (electrical converter) or a plug adapter for your travels, most often both. Most voltage adapters for travel convert 220-240 to 110-120, usable by your American and similar appliance. A plug adapter, on the other hand, allows you to plug into a foreign outlet.
• In Nepal, you will need a voltage converter, and plug adapter in order to use U.S. - like appliances.
• In some countries you may only need one or the other (voltage converter or plug adapter), but in Nepal you may require both. Note: you may need many different plug adapters if your travels extend to more than one country, but one voltage adapter is okay to work in one country.
• We recommend getting a universal adapter and converter kit if you plan to take many electronics. It can be found in many hardware stores, travel shops and online retailers. Virtually all laptop computers and some electric razors take universal voltages. Check your equipment to be sure. If the only electric device that you plan to take with you is an electric shaver, you may consider buying a different model which accepts universal voltages, to avoid carrying around a heavy and bulky voltage adapter. Always be sure to check with the manufacturer of the appliance for proper use and conversion.
  
  NOTE: You can find any of the transformers, plug adapter and converters in Kathmandu and other major cities.
   
• Electricity flow is not smooth in Nepal. Electricity often goes off and on. Voltage fluctuation is very common and it is advised that you use an adapter with quality power surge protector for your electronics.
• Nepal has not been able to produce enough electricity to meet the high demand, so in dry seasons there is power outage (load shedding) for hours, however hotels and businesses cover their electrical needs via fuel cells and generators.

Recap:
Voltage in Nepal: 220-240 Volts (U.S./Canada are 110-120 Volts)
Frequency in Nepal: 50HZ
Primary Socket Types in Nepal:

Nepal/India, Euro-plug, i.e. with round two prongs or three prongs
For Multi-voltage appliances (laptops, etc.) your need: A plug adapter
For 110-120V electronics your need: Plug adapter + step-down transformer
For Hair dryers, curling irons, etc your need.: Plug adapter + voltage convert