What to look for in a portable generator

By: Randall Johnston

Presented by
  • Earthmovers & Excavators

When it comes to generators there are a lot of different options on the market. Because every job is different, it’s important to know roughly how much power you are likely need onsite.

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Portable diesel generator

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Generators vary hugely in size and performance. From huge trailer mounted beasts, right down to your little esky-sized, highly portable unit.

It’s obviously not economical to be running something with a might higher output than what’s required, but conversely it’s frustrating to be using something that is struggling to keep up.We’ve put together the tips for anyone looking to rent or buy one.

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Diesel powered emergency backup electric generator on a portable trailer


To begin, it all starts with choosing the right generator for your specific power requirements. Write down all the items that you plan on using with the generator; verify the number of watts for each item, then add up your total power requirements. Ask the renter or seller for a forecast on fuel consumption, if they don’t know then this information should be available from the generator manufacturer.

Fuel consumption can sometimes be achieved by linking up several smaller generators, rather than using one high-powered one, so that’s always worth investigating as an option if it’s practical. It can also pay to get a generator that has a power management system (PMS), which optimises the fuel consumption of generators depending on the current load demand.

Note: Always add the necessary amount of oil, according to the model you are working with. Most will have an area that shows the oil level so you know how much to pour. Please note that the oil level should be checked before every use and changed after about 20 hours of continuous running.

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Reliable brand

While the make and model are not always that critical, the generator manufacturer's history and reputation should definitely play a role when your company is choosing to rely on used machinery. 

Since you are purchasing a product that you will most likely come to rely on for electric power at some point (whether you are buying a prime or emergency standby generator), now is not really the time to be cutting corners or taking big chances on unknown brands.  It's always a good idea to go with a trusted manufacturer which has a reputation for producing equipment that can stand the stress and test of time, so you can find parts and service that's readily available if necessary.

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Mobile diesel generator

Wear & Tear

A generator can undergo significant wear and tear during operation, so it’s important to check all mechanical components for wear and tear and to see if any of the mechanical parts have any cracks or corrosion built up.

If any part is found to be questionable, it should be replaced, ideally with components recommended by the manufacturer. The unit could still be perfectly reliable even if it has had an engine replacement, but it pays to do a close visual inspection and ask the seller/renter to give you a quick demonstration of the generator in action if possible.

Ideally the bearings and bushings should all be replaced, if this hasn't already been done by the dealer. The bearings and bushings are subject to stress during the generator operation and it is very difficult to test these parts for any stress they have been subjected to.

Check or have someone check the welds for integrity; inspect electrical components and windings for integrity and test wire insulations for breakdown if possible.


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