Selecting a generator that can handle all your power generation needs is one of the most important aspects of the purchasing decision.  Whether you are interested in prime, temporary, or standby power, if your new generator can’t meet your specific requirements then it simply won’t be doing you any good because it can put undue stress on the Generator and even damage some of the equipment connected to it.  Unfortunately, determining exactly what size of generator to purchase is often exceedingly difficult and involves a number of factors and considerations.

Making a choice amongst single-phase, three-phase, kW, KVA, welder, standby, or motor starting generators can be confusing. To prevent such confusion, Powerlite has written this article to help you get a better idea of how the sizing process works and some key things to keep in mind.  This is not a substitute for a certified electrician, which we always suggest talking to before Purchasing (Powerlite can assist you here), but it should provide you with enough information to get an understanding of some of the key factors that are involved.

Generator Size Variations:

With the latest advancements in the field of power generation, Powerlite supplied and built generators are now available in a wide range of sizes. Powerlite Generators with power supply capacities of 1Kva to 80Kva are readily available for home use, while Australian industrial generators are anywhere from 50Kva to over 3 Megawatts. Powerlite can build multi set applications where up to 32 generators can be synchronized to work as 1 (96 Megawatts).  Portable Generators are available for homes, caravans and small offices, but larger businesses, data centers, buildings, and mining applications need to use a much larger sized Diesel generator/generators to meet their power requirements.

Generator Sizing:

Many people believe smaller generators can be used for standby power because they are not running all the time. This is not only wrong but can be very damaging. Unfortunately, the generator under-sizing is one of the most common mistakes committed by purchasers.  Not only does it involve the risks of damaging your new generator, but it can also damage other assets connected to it, create hazardous situations, and even limit the overall efficiency of the unit and/or the business relying on it.  If nothing else, the key thing to remember here is that more is always better than less.

How to Determine the Right Generator:

While there is no substitute for the services of a qualified electrician (Powerlite can assist you here) the following information will allow you to make a more qualified decision with a better understanding for choosing the right generator for your application:

Know You’re Requirements:

Going to an auction site or a dealer and buying the cheapest or the best (so they say) is not the option.

  • Make a list of the items that need to be powered by the generator
  •  Make a note of the starting and running Current of the respective items
  • Calculate the total power requirements in Watts or KW
  • Phone or Email Powerlite and one of our technical representatives will be able to assist you.

How to Find the Starting and Running Current: 

Getting the right starting and running current of the devise you require to run is very important, these can be found on the manufacturer’s plate or in the hand book provided with the item. If these cannot be found call Powerlite and we will be able to assist you.

Power Requirement Charting:

It often happens that you lose the owner’s manual or for some reason cannot find the power requirement specification of the tools and/or other electrical devices you’re running. Below is a sample power consumption chart.


Appliance / Power Tool Average Appliance / Power Tool Average
Watts Watts
Air Conditioner (reverse cycle) Iron 900-1200
Small – 1 HP 2000 Kettle 1200-2400
Medium – 2 HP 4000 Lighting
Large – 3 HP 6000 Fluorescent 40
Air Cooler (evaporative) 150-800 Compact Fluorescent 9-15
Angle Grinder (100mm) 1200-1800 incandescent 40-100
Angle Grinder (230mm) 2400 Halogen 250-400 Electric Motors
Brick saw 2400-5000 Floodlights – small 250 The average Watts that have be used to size a
Clock Radio 60 Floodlights – large 500-1500 generating set takes into account the power
Clothes Drier 2400 Microwave 1300 lost within the electric motor, the extra power
Coffee Machine 600-2400 Oven required by the motor each time it is started
Computer 150-300 Mini 800 and the additional power that the generator can
Concrete Mixer 1200-2400 Conventional 2400 provide above its normal rating.
Dishwasher 2400 Fan Forced 1800
Drill – Hammer 650-1400 Radio 60 The Watts shown here assume that the motor
Drill – Power 450-800 Range will, once started, be required to operate at its
Fan Small hotplates 1000 full output power continuously.
Exhaust 40 Large hotplates 2000
Ceiling 100 Cooktop – Ceramic 1000-2000 Watts on Average Average
Food Blender 450 Cooktop – Electric Solid 2000-4800 Motor Name Input Power Watts
Food Processor 450 Refrigerator (4 star rating) 150-650 Plate Required
Freezer (4 star rating) 150-300 Sewing machine 75 180W (¼HP) 240W 720
Frypan – electric 1350 Shaver 15 250W (⅓HP) 340W 1000
Hairdryer 1200-1600 Stereo 100 370W (½HP) 500W 1480
Hand Saw 2400 Television 75-300 550W (¾HP) 740W 2200
Heater Toaster 600-1250 750W (1HP) 1000W 3000
Oil filled column 1000-2400 Vacuum Cleaner 1000-2400 1100W (1½HP) 1475W 4400
Radiators / portable fan 600-2400 Washing Machine 500-2400 1500W (2HP) 2000W 6000
Space 3600-7000 Welder* (240V/140 Amp) Min 6000 1870W (2½HP) 2500W 7450
Hot Water Service 2400-4800 2200W (3HP) 2950W 8500





Different ways of Calculating:  Depending on the number of items to be run by the generator, the starting sequence, and the type of item (motor start, multiple motor starts, UPS, heaters or lights).

All the above needs to be considered to make the correct selection for your needs.


Advantages of choosing the right size generator: Now that you have an idea on how to choose the appropriate size of generator to suit your needs, here is just a few of the benefits obtained by going through that process:


– No unexpected system failures
– No shutdowns due to capacity overload
– Increased longevity of the generator
– Guaranteed performance
– Smoother hassle-free maintenance
– Increased system life span
– Assured personal safety
– Much smaller chance of asset damage

Where to Buy a generator or power solution package:  Since you are not only purchasing an asset that is costly, you have taken into consideration the implications to your home or business of selecting

(A) the wrong size (B) from the wrong supplier.
The people at Powerlite have been in the business for over 50 years.

Here are just a few of the reasons why you should always consider Powerlite. as your first stop for all your power generation and servicing needs:

  • 50+ years of industry experience
    Full service from multiple locations – Sydney and surrounds
    Highly qualified technicians
    Testing equipment and installation tools
    Helpful support and knowledgeable staff
    We test all our products prior to dispatch
    Always competitively priced!


There are obviously numerous considerations to account for when selecting the appropriate generator for your needs.  If you are having a difficult time with it or would like more specific suggestions and recommendations for your situation, Contact Powerlite today 1300 436 738 and one of our knowledgeable staff will be more than happy to assist.


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