Tips for Building
Highest score · Best price per kW
maXpeedingrods 3500 W inverter
10/10
score calculated from published figures
Plenty of watts for the money, figures to take with care
Scored comparison
Eight inverter generators, scored on their figures
On a site with no supply, or during a power cut, this is the machine that runs the mixer, the saw and the freezer. The number printed large on the casing is almost never the one that matters.
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Second-highest score
Pramac PMi3000
9/10
score calculated from published figures
A real 2.8 kW, an almost empty spec sheet
Look at continuous power, not maximum power. Maximum power lasts a few seconds, long enough to start a motor. What keeps a circular saw running for an hour is continuous power, and it sits 10 to 25 percent below the figure on the box.
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8 of 8 machines
| Machine | Score | Continuous power | Retrieved price |
|---|---|---|---|
| 10/10 | 3,200 W | $638.24See on Amazon | |
| 9/10 | 2,800 W | $652.58See on Amazon | |
| 8.5/10 | 3,200 W | $705.49See on Amazon | |
| 7.5/10 | 1,800 W | $369.01See on Amazon | |
| 7.5/10 | 1,900 W | $784.00See on Amazon | |
| 7/10 | 1,600 W | $426.20See on Amazon | |
| 6/10 | 2,800 W | $2,876.03See on Amazon | |
| Not scored: too few figures | not published on the page we consulted | $376.86See on Amazon |
No item matches these filters.
How this score is calculated
We have not run any of these machines, and we present nothing as if we had. The score comes from four measurable criteria: continuous power 40 percent, price per continuous kW 25 percent, noise at 7 metres 20 percent, weight 15 percent. Each value is mapped onto a 4 to 10 scale against the other machines in the panel.
When a maker does not publish a figure, or publishes it ambiguously, that criterion drops out and the remaining weights are renormalised. Below 60 percent of the scale, or without continuous power, no score is given at all: otherwise the maker who publishes least would rank best.
The noise trap
Makers do not measure noise the same way. Some give sound pressure at 7 metres, between 58 and 73 dB(A) in this panel. Others give sound power, LwA, between 70 and 96 dB(A) for the same machines. These are not two noise levels, they are two different quantities. We only score pressure at 7 metres, and only when it is published as such.
Two examples. Honda's page for the EU30is swaps its own labels, calling 74 the sound power and 91 the noise level, when the higher figure has to be the sound power. And maXpeedingrods quotes 58 dB(A) in eco mode at 25 percent load: the most flattering condition there is.
Before you plug anything in
- Never in an enclosed space. Not a garage, a basement or a shed, even with the door open. A generator gives off carbon monoxide, an odourless gas that kills. Outside, away from doors and windows.
- Never wired straight into the consumer unit. Back-feeding a house through a double-male lead sends current into the grid and endangers the people working on it. The connection goes through a changeover switch fitted by a qualified electrician.
- An extension lead rated for the load. A lead that is too thin heats up. On site, 2.5 mm² cable and a sensible length.
- Store fuel outside in an approved can, and refuel with the engine off and cool.
Where this tool is used, job by job
Choosing the machine is one thing, using it another. Here are the pages where it comes up, with the steps in order and the rest of the kit.
Laying a concrete slab
Dig out, compact, form up, reinforce, pour, level, cure: seven steps and the machines that are better hired.
Read moreFrequently asked questions
How much power does a self-build site need?
Add up the machines that run at the same time, then allow a margin. An 800 W mixer and a 1,400 W circular saw already ask for 2,200 W continuous, plus the start-up peak. For that pair, a machine around 2 kW continuous is too tight; aim for 3 kW.
Can an inverter generator run a laptop?
Yes, that is the point of it. Inverter technology produces a clean sine wave, usually under 3 percent distortion, which electronics tolerate. A conventional AVR generator suits power tools but not always sensitive devices.
Can I connect a generator to my house?
Not directly. It goes through a changeover switch fitted by a qualified electrician, which isolates the house from the grid while the generator runs. Without it, current flows back into the public network, which is dangerous and illegal.