Choosing a generator can often be a bit of a minefield. In this article we attempt to demystify the entire process of choosing which particular generator would be suitable for your requirements.
2. How do noise levels affect your choice?
3. Portability capabilities required?
4. How many hours do you need it to run for?
5. Which type of fuel do you want to use?Asking these 5 questions will usually solve your problems… And here is how!
Generator Power
Generators commonly range from 1 KVA (the size of a small suitcase) to 150 KVA (the size and weight of a ford transit van), however sizes are rather limitless. Portable sets tend to ranged from 1 KVA to around 5 or 6KVA.
KVA stands for Kilo Volt Amps. The term is used when talking about and sizing equipment for power generation. The more common term Watts is used when referring to power use and consumption. When purchasing a generator, the rated Watts will usually be noted in the specifications. To make life easier, we recommend looking at the rated Watts to save confusion. For example; a 1 KVA generator should be rated at 900 Watts, therefore 900 Watts is your maximum limit to load on the generator.
You are limited to the watts that a generator can provide, if a generator can provide 900 Watts, you may only load the generator with appliances that require (and not exceeding) a maximum of 900 Watts. A 900 Watt generator should be capable of powering a laptop, a TV and some lights, but would not be able to power a kettle or a microwave. The best way to find out how many Watts your appliances require is to either refer to your manual supplied with the equipment, contact the supplier or an electrician to perform a load test on your appliances. A load test would determine how many Watts are required to power everything at once and/or singularly, and then matching up a generator is easy enough once you know how many Watts the equipment requires and how many Watts each generator can provide.
A load test can be particularly useful if you are powering anything with a motor. There are many different designs of motor, each with different characteristics. Some motors, e.g. Induction type motors (capacitor start/capacitor run) require additional current to start them, therefore requiring a larger generator. Motors fitted to hand tools generally do not require any additional start-up current. Consequently, it is recommended to ask the supplier/manufacturer of the equipment (or perform a load-test) that you wish to run whether it requires additional start-up current. As a rough guide only, allow for a generator that has a continuous rating of 2 ½ to 3 times the motor rating.
Finally, what type of appliances are you looking to power? If you are powering a few lights and a kettle, any generator should be fine. If you are on the other hand powering a laptop and a flat-screen TV, you would require “clean power”. Clean power is electrical current that is consistent and has a stable “sine wave” or signal. If the lights or other basic appliances in your home were being powered by a generator and there was a fluctuation in the AC power, you’d probably see the lights dim and then return to full brightness – no problem! However, if your computer was being powered by a generator and the voltage fluctuated, chances are the computer would either shut down or at least interrupt the program you were working in.
Engineers have developed a revolutionary form of inverter technology. This process takes the raw power produced by the generator, passes it through a special microprocessor that provides ultra-clean power that boasts a sine wave equal to or better than the current from your household AC wall outlet. This means that, you can operate a computer or laptop direct from a generator.
AVR is basically the same output as an inverter machine, generators equipped with AVR (Automatic Voltage Regulator), this feature limits the variation of the voltage of your generator to + or – 2 %. With a generator equipped with AVR you can run sensitive equipment such as computers.
Generator Noise
The decibel which is normally abbreviated dBA is the unit used to measure the intensity of a sound. The human ear is incredibly sensitive; a person’s ears can distinguish between wide ranging sounds such brushing their fingers on a notepad to the loudest explosion or Jet aircraft. To put these differences into perspective a jet aircraft is 1,000,000,000,000 times louder than the quietest audible sound.
Here are some common sounds and their decibel ratings:
| Sound Level | |
| 190 dBA | Heavy weapons, 10 m behind the weapon (maximum level) |
| 180 dBA | Toy pistol fired close to ear (maximum level) |
| 170 dBA | Slap on the ear, fire cracker explodes on shoulder, small arms at a distance of 50 cm (maximum level) |
| 160 dBA | Hammer stroke on brass tubing or steel plate at 1 m distance Airbag deployment very close at a distance of 30 cm (maximum level) |
| 150 dBA | Hammer stroke in a smithy at 5 m distance (maximum level) |
| 130 dBA | Loud hand clapping at 1 m distance (maximum level) |
| 120 dBA | Whistle at 1 m distance, test run of a jet at 15 m distance |
| Threshold of pain, above this fast-acting hearing damage in short action is possible | |
| 115 dBA | Take-off sound of planes at 10 m distance |
| 110 dBA | Siren at 10 m distance, frequent sound level in discotheques and close to loudspeakers at rock concerts, violin close to the ear of an orchestra musicians (maximum level) |
| 105 dBA | Chain saw at 1 m distance, banging car door at 1 m distance (maximum level), Racing car at 40 m distance, possible level with music head phones |
| 100 dBA | Frequent level with music via head phones, jack hammer at 10 m distance |
| 95 dBA | Loud crying, hand circular saw at 1 m distance |
| 90 dBA | Petrol Lawnmower |
| 85 dBA | 2-stroke chain-saw at 10 m distance, loud WC flush at 1 m distance |
| 80 dBA | Very loud traffic noise of passing lorries at 7.5 m distance, high traffic on an expressway at 25 m distance |
| 75 dBA | Passing car at 7.5 m distance, un-silenced wood shredder at 10 m distance |
| 70 dBA | Level close to a main road by day, quiet hair dryer at 1 m distance to ear |
| 65 dBA | Normal Conversation |
| 60 dBA | |
| 55 dBA | Low volume of radio or TV at 1 m distance, noisy vacuum cleaner at 10 m distance |
| 50 dBA | Refrigerator at 1 m distance, bird twitter outside at 15 m distance |
| 45 dBA | Noise of normal living; talking, or radio in the background |
| 35 dBA | Very quiet room fan at low speed at 1 m distance |
| 25 dBA | Sound of breathing at 1 m distance |
| 0 dBA | Auditory threshold |
If you take a look at the decibel scale, the smallest audible sound which is near silence registers at 0 dB. This is an increase of 10 decibels equates to a 10 fold increase in noise to your ear. An important thing to remember is that generators are measured and compared within the industry @ 7 metres. To comply with EEC regulations all generators have to be marked in LWA, this is a different measurement of sound which is taken from a different distance. For example, a quiet Honda EU20i generator is rated at its lowest at 52 dBA @ 7 metres on the LWA scale, this would equate to approx 88 decibels. Please beware of this as all products have LWA marked on them, many do not have the industry rated @ 7 metres level.
Generator Portability
This is probably one of the most common issues when it comes to suitcase generators and simple portable open-frame generators alike. Obviously when you require little power, you will only require a little generator.
Be sure to always look at generator specifications to determine the weight and dimensions of any generator you purchase, it can be a costly process to return an item ordered in error… If in doubt, always ask! A good clue though is to look at the design of the generator, if it only has one handle; it’s designed to be a one-person lift. The average human can lift around 65kg; bear this in mind when purchasing a generator. There is still hope though if you require a more powerful generator to be portable, wheel kits are available for most models – so be sure to ask about them if you are concerned.
Using A Generator
The final things to consider are how many hours you need the generator to run for in the case of an emergency or in everyday application and fuel type. Generators are often available with different size fuel tanks. Many generators are available with the option of a standard fuel tank or a long-run fuel tank, naturally the volume of fuel in the tank determines the length of time a generator can run for. Be sure to check the specifications.
There are 3 main types of generator fuel for portable sets; petrol, LPG and sometimes diesel (though diesel tends to be larger and louder). There are benefits to all three and it’s important to consider your options.
Petrol is probably the most commonly used type of portable generator. Petrol engines are capable of running quietly and very efficiently with today’s technology.
LPG is commonly used as an alternative to petrol. These are often petrol generators that have been converted for LPG use, remember that most conversions are full conversions and are NOT dual fuel.
LPG has many benefits:
· Lower running costs (bottled gas is about 50% cheaper than petrol).
· Great flexibility from extended running time (according to cylinder size).
· Cleaner emissions allows use in sensitive situations (such as around food).
· Less disruption from quieter running.
· Minimal risk of fuel spillage/pilferage.
· Lower maintenance costs from extended life sparks plugs and oil.
· No petrol storage problems.
· Easier refuelling.
Diesel sets tend to be more expensive and bulkier. However they boast better efficiency and longer lifetime.
Just Generators say:
Please always remember to check what size, weight, noise level limitations and how many Watts required BEFORE purchasing a generator… Otherwise, you may find yourself disappointed and in a muddle with a generator that is too loud, too big, or not powerful enough.
If you need any advice when choosing a generator please call us on
01263 820202
or visit us at
Your guide provided excellent clarity on the many important factors to consider when choosing a generator. I appreciate the thorough examination of power needs, noise levels, portability requirements, run times, and fuel types. Following these practical tips will ensure one selects a durable, versatile generator that reliably meets their specific backup power needs. The comprehensive overview is extremely helpful.