How to select the right generator in South Africa

Eskom has published a document titled “Selecting the right type of generator”, providing guidelines on which generators to buy, and how to connect them to your home.

Residential generators are available in a variety of sizes, with power supply capacities ranging between 5kW and 50kW. These generators are petrol or diesel driven.

Eskom warned that generator under-sizing is one of the most common mistakes committed by buyers.

“Not only could it damage your generator, but it can also damage other assets connected to it, creating hazardous situations,” said Eskom.

Eskom said generator users must remember that more power generation capacity is always better than less.

Things to consider when buying a generator

Eskom said home owners must consider the following when buying a generator:

  • Safety: Generators need to be correctly installed and connected to the building via a suitable and approved change-over switch, including installation of an over current protection circuit breaker in the main distribution board by a certified electrician.
  • Total electrical load to be connected.
  • Voltage, frequency, and phase.
  • Does the generator need to start automatically? If so, then an automatic mains failure mechanism needs to be installed.
  • Suitable location for the generator – outside or in vented area (not to be installed in an enclosed area or indoors).
  • Acceptable noise levels.
  • Altitude and running time.

What should you power with the generator?

  • Kitchen, bathroom, and sitting room lights
  • One plug in kitchen for kettle or cellphone charger
  • Refrigerator/freezer
  • Television and decoder
  • Garage door opener
  • Microwave/oven
  • Computer
  • Security – alarm systems/electric fencing/lighting

How big a generator should you get?

The capacity of the generator depends on the total of the electrical loads you want to power simultaneously, measured in Watts.

All heating appliances – such as stoves, heaters, dishwashers, geysers, kettles, tumble dryers, toasters and hairdryers – draw the most power, and should be switched off.

PCs and electronic equipment don’t use much power, but are voltage sensitive. If the generator does not deliver a constant voltage and there are dips and spikes, equipment may suffer damage.

Item Quantity Starting Wattage Running Wattage
Refrigerator or freezer (Energy Star) 1 1200 192
Microwave oven 1 1000 1000
Incandescent lights 6 360 360
Television 1 120 120
Computer 1 250 250
Garage door opener 1 1420 720
DVD player 1 350 350
Total 4700 2992

Typical generator sizes needed

The table below provides an overview of the typical generator sizes needed for households.

Generator sizes needed
Small portable generator (3kW to 4kW) Mid-sized portable and small stationary generator (5.5kW to 8kW)
What it can power: What it can power:
  • Refrigerator (600 watts)
  • Microwave (1500 watts)
  • Sump pump (600 watts)
  • Several lights (400 watts)
  • TV (200 watts)
  • Refrigerator (600 watts)
  • Microwave (1500 watts)
  • Sump pump (600 watts)
  • Several lights (400 watts)
  • TV (200 watts)
  • Portable heater (1300 watts)
  • Computer (250 watts)
  • Heating system (500 watts)
  • Second pump (600 watts)
  • More lights (400 watts)
Large portable generator (10kW) Large stationary generators (10kW to 15kW)
What it can power: What it can power:
  • Refrigerator (600 watts)
  • Microwave (1500 watts)
  • Sump pump (600 watts)
  • Several lights (400 watts)
  • TV (200 watts)
  • Portable heater (1300 watts)
  • Computer (250 watts)
  • Heating system (500 watts)
  • Second pump (600 watts)
  • More lights (400 watts)

Add a choice of:

  • Small water heater (150 litre – 200 litre hot water geyser – 3000 watts)
  • Central air conditioner (5000 watts)
  • Electric range (5000 watts)
  • Refrigerator (600 watts)
  • Microwave (1500 watts)
  • Sump pump (600 watts)
  • Several lights (400 watts)
  • TV (200 watts)
  • Portable heater (1300 watts)
  • Computer (250 watts)
  • Heating system (500 watts)
  • Second pump (600 watts)
  • More lights (400 watts)

Add a choice of:

  • Small water heater (150 litre – 200 litre hot water geyser – 3000 watts)
  • Central air conditioner (5000 watts)
  • Electric range (5000 watts)
  • Clothes washer (1200 watts)
  • Electric dryer (5000 watts)

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How to select the right generator in South Africa