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Buying a Petrol Generator - What you need to know

Buying a petrol generator doesn’t need to be as complicated as you might think, but there some important factors to consider. Use our simple buyer’s guide to make sure you get the right generator for you, your site and your needs. 

What are your power requirements?

To address this question, you actually need to think about two different things – how much power your equipment needs but also what type of equipment are you using. A good place to start is by looking around your site and deciding on a realistic combination of critical equipment, finding the power usage of each and adding them together. Make sure to add in a decent (circa 1000W) buffer, both to account for additional and new equipment, and to allow for kit that might have higher start-up requirements than the typical running power.

Petrol generator being used near a car


As for the second part – if you are using laboratory equipment, computers, laptops or servers, you need to think about the quality of the power supply. These more delicate devices can be damaged or destroyed by the slightest surge, so you’ll need to look at a generator with an Automatic Voltage Regulator (AVR) fitted to the alternator. This will ensure that the power output is managed and even, as close to the quality of the usual mains power supply as possible.

Generator Engine quality

Whether you are planning to use your generator as an emergency failover or you just need power where you can’t easily get mains electricity, you’ll want the generator to be capable of running consistently over sustained periods of time. Some lesser quality models can overheat or simply stop working after a very short time, leaving you powerless. Look at generators with engines by well-known manufacturers – you should be able to rely on these.

Run time

Leading on from engine quality, you need to think about how long you need the generator to run for. If it is for emergency failover use, you might not need it to run for ten+ hours, but if you are powering a construction site, outdoor event or using it for other leisure uses, you need to think about maximum run-time. This can go hand-in-hand with fuel tank size, but be aware that sometimes a larger fuel tank will actually have a shorter run time due to the higher power output. Consider all the elements together to make sure you get the right model for you.

Petrol generator being used with angle grinder


Output connections

You should think carefully about the sockets you need, in terms of both type and quantity. If you plan to use the generator to power just one piece of equipment you obviously don’t need a multi-socketed, dual voltage unit. If you are going to be powering a number of tools and lighting rigs on a construction site, you must have the sockets available to do so.

Also think about health and safety rules and regulations – construction and some other industrial sites have to run from 110-volt sockets (as opposed to the standard 230 volts), so you’ll need a generator which can switch over as necessary.

As with the extra voltage buffer we suggested in the first point, add a socket or two to your tally in case you need it down the line.

Generator Build quality 

A poorly designed and built generator can be loud and can vibrate a lot, as well as being vulnerable to damage from impacts. You’ll want a model with vibration and sound dampening, and the better the build quality the more likely it is to stand up to the rigours of use. Models with a larger, tubular frame can protect from the inevitable bumps and knocks found on a busy site, and make them easier to carry.

Generator with good build quality



If you would like further advice about petrol generators, or if you have any questions, get in touch with the experts at First Mats either by way of chat on the website or by e-mail to info@firstmats.co.uk