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Generator Buying Guide

There are a number of things to consider when choosing the generator that's right for you. Most importantly, you'll need to know the power requirements of the equipment you'll be running. It's easy to be intimidated by a barrage of technical electrical information, but this simple guide will help you make an informed and confident purchase.

The main things you need to consider are:

1. Power output (either measured in watts or kVA)

There are two main power measurements for generators: startup watts (also known as peak power) and running watts.

When choosing a generator, you'll need to choose one that can handle the startup wattage of the equipment you're planning to power. As a rule of thumb, the startup wattage is generally around 2-3 times the running wattage of a device. This varies however, and your best bet is to check the manual of the device you're planning to power for an exact value.

At the bottom of this guide is a list of the approximate values for the running wattage of common household appliances.

2. Fuel type - petrol or diesel?

Most portable generators run on petrol, but it's worth looking at diesel models as well. Diesel engines are generally harder to start and are a little bit more expensive than petrol. But they last longer, especially with continuous use. For larger models diesel is going to be cheaper to run due to lower fuel costs.

We recommend using a conditioner with diesel fuel, to stop the diesel growing fungus and degrading its quality (this happens naturally).

3. Backup (stationary) or portable?

If you're looking for backup household power, portability won't be a priority. Stationary generators have numerous advantages. They’re generally quieter, easier to start and more powerful than portable options. Plus if they’re hardwired into your home or business (don’t do this yourself!) there will be no mucking around with extension cords when the power is out.

For camping, motorhomes, marine, tradies, or basic home use you’ll likely be wanting something portable. The biggest decision to make with portable generators is what type of start up you want it to have. Both battery start and pull start options are available.

4. Traditional or Inverter?

Inverter technology makes these models perfect for powering sensitive electronics like computers, TVs, microwaves, etc. They produce a clean sine wave of electricity which guarantees there will be no power surges.

Standard / traditional generators run at full speed regardless of how much power you need. But an inverter uses a self-governing smart throttle which adjusts when you turn on a light or appliance. This means you save on fuel, it's quiet, runs smoothly, and is better for the environment.

5. Single phase or three phase?

Single phase generators produce single phase power which is similar to that used by most common household appliances. Hence single phase generators are suitable for most homes and small businesses.

Larger commercial operations often require three phase power, hence have the need for a three phase generator.

Three phase generators can be run as single phase however the power output will be roughly a third that of when it runs as a three phase.

Power required for common appliances

The list below provides approximate values for the running wattage of common household appliances:

Remember your generator needs to have enough power output to handle the startup wattage (approximate 2 to 3 times the values below)

Common Appliances:

  • Clothes Dryer 4000W
  • Dishwasher 1200 - 3600W
  • Electric Oven 2000W
  • Heater 150 - 2000W
  • Microwave 600 - 1500W
  • Toaster 800 - 1500W
  • Electric Frying Pan 1200W
  • Iron 1000W
  • Blow Hair Dryer 1000W
  • Stove Range 800W
  • Coffee Maker 800W
  • Vacuum 200 - 800W
  • Washing Machine 500W
  • Fridge/Freezer 200 - 700W
  • Television 100 - 450W
  • Computer + Monitor 100 - 400W
  • Blender 350W
  • Electric Blanket 200W
  • Sewing Machine 100W
  • Light Bulb 18 - 60W
  • Laptop 50W
  • Shaver 15W

Outdoor Power Tools:

  • Electric Mower 1500W
  • 10" Bench Saw 1500W
  • Weed Eater 500W
  • Hedge Trimmer 450W
  • Belt Sander 380W
  • Drill 330W

When you browse the generators on Trade Tested, you'll see they are listed by their power capacity in kVA (kilo volt-amperes). This is standard practice outside America. You can find a generator's capacity in watts (both startup watts and running watts) in the description section of each generator on our site.

Choosing the wrong sized generator is an easy mistake to make. Most models can sustain only 80% of their maximum power for the long haul. If you constantly push your generator to over 80% power, it's not going to last as long, and risks damaging the appliances connected to it. As a general rule, bigger is always better.

Safety Tips

It's important to consult the operator manual for a full list of safety precautions, but here's a few basic tips worth following:

  • Don't run your generator indoors or in poorly ventilated areas. Avoid running it near windows, doors, and other openings where the exhaust can enter indoors.
  • Make sure the generator is placed on a level surface.
  • Avoid exposing the generator to excessive moisture, dirt, and dust.
  • Avoid overfilling the fuel tank and never fill up the generator when it is running or still hot from recent use.
  • Keep the generator a safe distance from open flames, pilot lights, and anything sparky.
  • Never connect a generator directly to your home's wiring. If you need to do this, hire an electrician and get them to install a transfer switch.
  • Use heavy duty outdoor extension cords to plug appliances into the machine. Or connect the generator to a power-transfer switch.
  • Do not overload the generator.
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