What Size Generator Do I Need?

When it comes to choosing a generator, bigger isn’t always better. There is a whole range of considerations that you need to take into account in pinpointing the right generator for your situation. Pick the wrong generator and you could end up overloading and overheating it. You could even damage it permanently. If you’ve got everything riding on a reliable and constant power supply, the last thing you need is a costly and inconvenient breakdown. Knowing what size generator will best suit your needs is crucial.

Basic generator terminology and choosing the right sized generator

It helps to have a basic understanding of electrical terminology in order to choose the right-sized generator for your situation. Here’s some of the most common terminology you’ll find associated with generators:

Kilo volt-amperes (kVA)

Generators are rated in kVA: It stands for kilo volt-ampere, or a thousand volt-amperes. It’s a measure of electrical power in a circuit. Basically, a generator’s rating in kVA will tell you how many appliances that generator will power at any given time.

Total electrical load – Watts (W), kilowatts (kW) and horsepower (HP)

In order to choose the right size generator, you have to ensure that its rating meets (and preferably exceeds) the total electrical load that it will be subjected to. You calculate the total electrical load by looking at the individual wattage of each of the appliances or tools that you will be running off the generator and then adding it together.

A watt (W) is a measure of electrical power. An electrical appliance’s wattage is the rate at which it uses electricity. Wattage can be found on an energy rating sticker on the appliance, on the appliance’s label or in its instruction manual. A Kilowatt (kW) equals 1000 watts. Appliances are rated in kilowatts (kW) and watts (W). Larger pieces of equipment, such as pumps, tend to be measured in horsepower (HP). Basically, 1HP is equivalent to 750 watts.

Once you have the total electrical load, you need to convert it into kVA. Your generator’s rating should exceed your total electrical load. How do you convert kVA to kW? You can do this quite simply, by multiplying a generator’s kW rating by .08. Alternatively, you can convert your appliances’ total electrical load (measured in kW) to kVA by dividing by .08.

Surge watts versus running watts

It’s important to note that some of your electrical appliances will draw much more power when they initially start up. This is called ‘surge’ or starting wattage. It’s a feature of appliances that have an electrical motor or fan. Heating and cooking systems, fridges and appliances with moving parts are particularly hungry for electricity when started as opposed to when they’re running. A generator will be rated as to its surge wattage as well as its running wattage, allowing you to calculate the additional burden of those appliances when they are first started.

Other factors to consider in choosing a generator

Making sure your generator is powerful enough to accommodate the total electrical load is important, but it’s not the be-all and end-all of choosing the right generator for your needs. You also need to consider a whole range of other factors. They include:

Type of generator – standard or inverter model: An inverter may be better suited to running appliances with electrical motors and fans because it can tolerate a higher initial power drain on starting. Also, the flow of electricity from a standard generator can be irregular which can be problematic if you’re trying to run a computer or other equipment with limited tolerance for electrical ups and downs.

Portability: You should also think about how you’re going to manoeuvre your generator into place, how you’re going to transport it and how many people you need to lift it.

Number of outlets: The number of appliances you want to run off a generator might be limited by the number of power outlets a particular model has.

Diesel or petrol: Generally speaking, a diesel generator will perform better than its petrol counterpart when running at maximum capacity over a long period of time.

Starting mechanism: You can choose between recoil models (like a lawn mower, started by pulling a cord) or electric start models (key start with a battery). Electric start models are particularly good if you’re elderly or otherwise incapacitated.

Size of fuel tank: This dictates how long your generator can run before it needs to be re-fuelled. It’s an important consideration because you’ll need to allow time for your generator to cool before you can refuel it.

How noisy your generator will be when running: You’ll also need to check the noise output of your generator against the local council noise restrictions applicable to the area where you will be using it.

Getting the generator guessing game right

Choosing the right size generator at the outset means you avoid costly and inconvenient breakdowns. It’s also cost-effective because you avoid paying extra for a bigger generator that you might not need. You also ensure a reliable flow of electricity when you need it most.

K Electrical can take the guesswork out of deciding what size generator suits your needs. We proudly supply an extensive range of Genelite and Honda generators. Our professional, friendly and experienced electricians can discuss your specific power needs and find the perfect generator match for you. What’s more, we’ve got the expertise to ensure that it’s properly installed at your home or business if need be.

Need to know what size generator will suit you? Call the experts at K Electrical on (07) 4152 2177.

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