Common uses of electrical energy and voltage levels

Electrical energy is used in domestic, commercial and industrial sectors. The supply voltage increases with the size of the load: small loads at low voltage (LV), larger loads at medium (MV) or high voltage (HV), to keep current and losses low. Voltage levels given below are those used in Nepal (NEA).

Domestic use

Examples:

• Lighting: LED, CFL lamps.
• Heating: water heater, room heater, electric iron, induction cooker, rice cooker.
• Motors: fans, mixer-grinder, washing machine, water pump, refrigerator compressor.
• Electronics: TV, computer, mobile chargers, internet routers.

Voltage: 230 V single-phase, 50 Hz; houses with large load (over about 10 kW) may get 400 V three-phase.

Commercial use

Examples:

• Lighting and signboards in shops, offices, malls.
• Air-conditioning, ventilation, refrigeration (cold stores, supermarkets).
• Lifts and escalators, water pumps.
• Computers, servers, ATMs; hospital equipment (X-ray, MRI); commercial kitchens in hotels.

Voltage: 400/230 V three-phase for most; large buildings (hotels, malls, hospitals) take 11 kV with their own transformer.

Industrial use

Examples:

• Electric drives: pumps, compressors, conveyors, cranes, machine tools, rolling mills, crushers.
• Electric heating: arc and induction furnaces (steel), resistance ovens, dielectric heating.
• Welding: arc, resistance welding.
• Electrochemical: electroplating, electrolysis, battery charging.
• Process control, lighting.

Voltage:

• Small industries (workshops, mills): 400 V three-phase.
• Medium industries: 11 kV.
• Large industries (cement, steel): 33 kV, 66 kV or 132 kV.
• Large motors inside a plant may run at 3.3 kV, 6.6 kV or 11 kV.

Summary table

 Grid 132/66/33 kV --> large industry
     |
   11 kV ------------> medium industry, big commercial
     |
  400/230 V ---------> homes, shops, small industry