How To Choose The Right Size of Generator
How to Choose the Right Size of Generator
Step 1: Make a Checklist of Electrical Devices & Appliances You Will Need to Run
The first thing you need to do is decide what you need to power when the electricity is out. This will depend on personal preference and your situation, but one would usually prioritise like this:
- Lights
- Refrigeration
- Cooking
- Entertainment
- Heat
- Cleaning
Remember: Cooking and heating equipment is extremely demanding compared to the rest of your appliances. Only power those when necessary or ensure your generator is large enough to run them with everything else.
Step 2: Learn How Much Power Each Device Draws and Add It All Up
After listing your appliances, the next step is to find out how much power each one uses. For example, a microwave (1 500 W) and a fridge (2 000 W) together require 3 500 W. You would therefore need a generator that delivers at least 3 500 W. We recommend a generator with 20% more power than your minimum to cover startup surges and prevent overloading.
Example Appliance Wattage Table
| Appliance | Running Wattage | Starting Wattage | Notes |
|---|---|---|---|
| Fridge | 2 000 W | 2 500 W | Compressor draw on startup |
| Microwave | 1 500 W | 1 500 W | Same as running wattage |
| TV | 150 W | 150 W | Modern LED TVs are energy efficient |
| Lights (5 x LED) | 100 W | 100 W | Assuming 20 W per bulb |
| Total | 3 750 W | 4 250 W | |
| Recommended Generator Size: 5 100 W (with 20% buffer) | |||
2.1 Why Is the Initial Start So Important?
Some appliances have a higher starting wattage. For example, a fridge might run on 2 000 W but spike to 2 500 W at startup due to the compressor. Be sure to include starting wattage in your total power calculations.
2.2 How to Measure an Appliance’s Power Draw?
- Check the sticker or plaque on the appliance or its packaging.
- Refer to general appliance wattage guides online.
- For unknown items, use a clamp meter to measure amps and apply the formula: Watts = Amps × Volts.
South African voltage is AC 220 V (50 Hz). For example: a device measuring 2.2 amps at 220 V = 484 W.
Advanced users may also measure directly on the power distribution board. Warning: This is dangerous without proper knowledge and should only be done by a qualified electrician.
Once you’ve calculated your total power needs, you’ll be ready to choose a generator that fits your requirements. Always size up — better to have more capacity than not enough.
Something to Consider
There are various generator types:
- Portable Generators – Versatile and suitable for multiple applications.
- Standby Generators – Permanently installed and offer reliable backup power.
- Inverter Generators – Quiet, efficient, and provide clean power for sensitive electronics.
Step 3: When You Know How Much Power You Require, Explore Our Generator Range
Once you know the size generator you need, visit our product listings to compare models. We stock both diesel and petrol options. Silent diesel types are ideal for noise-sensitive environments. Choose the fuel type that is easiest to source in your area.
Step 1: Make a Checklist of Electrical Devices & Appliances you will need to run
The first thing you need to do is to decide what you need to power when the power is out. This will rank depending on personal preference and situation but one would usually prioritise like this:
Lights>Refrigeration>Cooking>Entertainment>Heat>Cleaning.
*Remember! Cooking and Heating equipment is extremely demanding in comparison to the rest of your appliances. So be sure to only power those appliances when necessary, or buy a large enough generator to power these appliances alongside with the rest of your household.
Step 2: Learn how much power each device draws and add it all up.
After you have made a list of the appliances that you would like to power the next phase comes into play: Identifying how much power each of these appliances will be using. Example; A microwave and fridge together (1 500 W + 2000 W = 3500 W) Therefore you would require a generator that is 3 500 W at the MINIMUM. However we always recommend that you get a generator that can provide 20% more of a power output than you require, as a buffer for the inital start and to avoid overloading it.
2.1 Why is the inital start so important?
Something important to note is that while all appliances have a running wattage, some have a starting wattage as well. Appliances like refrigerators may require 2 000 W to run, but on start up they will use 2 500 W. This is the result of the compressor built into the fridge. So when adding up your running wattage, add the starting wattage of any appliances to the total to ensure your generator has the necessary requirements.
2.2 How to measure an appliances power draw?
You can find a sticker or plaque on the device itself or even the box/packaging you recieved the item in. Otherwise there is also a general guide for certain appliances that you can find online. Such as a power saving lightbulb using 20 W, or refrigeraters using 550 - 3 000 W (Depending on the model).
If a certain appliance that you need to power is not listed (uncommon device) either do an internet search for the manufacturer or use an electronic clamp meter to measure the current while the appliance is switched on. Measure the current (Amps @ AC current). This can then be used to find the wattage value via this equation: watt = amp × volt. Voltage in South-Africa is AC 220 V (50 hertz).
Example: A device that measures 2.2 amps at 220V = 484 watts.
Alternatively, as a more advanced user you can measure your power draw directly on your Power Distribution Board. However this is dangerous to the uninformed and best suited to a qualified electrician (but will yield a very accurate result).
Once you have a sum of total power requirement for your home/business you have the information needed to make the decision on a backup power generator!
The generator is manufactured to handle a brief surge of power but only for a few seconds. Keep to the manufacturers specifications and you will never overload the generator. Choosing the correct size generator is crucial, always remember that you would rather have a generator that can handle more wattage than you need rather than one that falls short.
Something to Consider:
There are different types of generators, including portable generators, standby generators, and inverter generators. Choose the type that best suits your requirements. Portable generators are versatile and can be used in various applications, while standby generators are usually more powerful and provide backup power during outages. Inverter generators are known for their clean power output and quiet operation.
Step 3: When you know how much power you require take a look at our range of generators
Once you know how much power or the size you need, head over to our power generator range page and make a selection. We have similar models in Diesel and Petrol. Either fuel does not make a difference in the working of the machine however for Silent type a diesel machine is more beneficial. Choose a machine that you can easily obtain fuel for based on your location.
Generator Prices and Specs: Adendorff Generator Range
Thank You for Reading