Most people get this wrong.
They don’t ask:
What do I actually cut?
They ask:
“What’s the biggest plasma cutter I can afford?”
Two completely different questions.
And the second one usually ends in disappointment.
Someone says:
“I want to cut 20mm steel.”
Sweet.
How often?
Because in most Kiwi sheds, real work looks like this:
3–6mm steel
Trailer brackets
Angle iron
Flat bar
Tube
Fixing a broken gate
Patching a trailer
Farm repairs
Whether you’re in Hamilton fixing a ute tray, down in Invercargill patching a stock crate, or in
Tauranga mucking around on a boat trailer…
That’s the stuff people actually cut.
Not 20mm plate every weekend.
If that sounds like you, you don’t need a monster machine.
Amps = Cutting Power (No Fluff Version)
More amps = more heat.
More heat = more ability to push through thicker steel.
Simple as that.
But here’s where people stuff it up.
They buy for the maximum thickness the machine claims it can cut.
Not the thickness they actually cut every week.
A 50 amp plasma cutter can clean cut around 10–12mm steel.
That already covers more than most home users ever touch.
Buying bigger than that “just in case” is usually just burning money for the sake of ego.
Bigger Doesn’t Automatically Mean Better Cuts
This one catches a lot of people out.
They assume:
Bigger amps = better cuts.
Nope.
Cut quality comes from:
Good air
Stable power
Decent consumables
Half-decent technique
You can have an 80 amp plasma cutter and still produce cuts that look like rubbish if everything else is wrong.
Bigger just means more heat.
If you don’t need the heat, you’re just carrying extra weight and cost for no reason.
The 20mm Fantasy
This is the funniest one.
Everyone wants to be able to cut 20mm.
Almost nobody actually does.
Most sheds live in the 3–6mm world.
Buy for that world.
Not the fantasy one you think you might need one day.
Because that “one day” usually never shows up.
And now you’ve got a bigger, heavier machine sitting there that cost you more and does the same bloody jobs as a 50 amp would have done.
NZ Power Reality (240V)
In New Zealand, we’ve got 240V single-phase power in most homes.
That’s perfect for plasma cutters up to around 50–60 amps.
Anything in that range runs happily on normal home power.
Once you start looking at bigger units:
They pull more current
They’re less forgiving on wiring They need proper supply
Some of the bigger industrial machines want three-phase.
Most houses don’t have that.
No point buying a big beast if your garage wiring is going to choke trying to feed it.
Rough Size Guide (Real Shed Stuff)
30–40 Amp
Good for:
3–6mm steel
Sheet metal
Light fabrication
Great hobby size.
50 Amp (The Sweet Spot)
Clean cuts up to around 10–12mm steel.
Handles almost all home and farm work.
This is the size most people in NZ should be running.
It’s the no-drama, sensible choice.
60–80 Amp
For regular cutting of:
12–16mm steel.
Only worth it if you actually cut that thickness often.
If you don’t?
It’s just extra cost and extra bulk.
Extension Leads Kill Performance
Here’s another one people ignore.
Long skinny extension leads cause voltage drop.
Voltage drop = weaker arc. Weaker arc = worse cuts.
Then people blame the plasma cutter.
No.
It’s the cheap skinny lead from Mitre 10 that’s choking it.
Short lead.
Thick cable.
Problem solved.
Air Is Half the Machine
You can buy the perfect size plasma cutter.
If your air is rubbish, your cuts will still look rubbish.
You need:
Dry air
Enough flow
Stable pressure
If air isn’t right, nothing else matters.
Plasma Cutter Air Pressure & Settings – Why Your Cuts Look Like Shit
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Consumables Matter More Than You Think
Worn out tips and electrodes make even a good machine feel useless.
Doesn’t matter if it’s 40 amps or 80 amps.
If the consumables are shagged, cuts will look rough.
We stock and ship plasma torches and consumables from New Zealand, so when yours are worn out, you’re not waiting weeks for parts to arrive.
That alone makes life easier.
The Ego Trap
Let’s be honest.
Bigger feels better.
But bigger also:
Costs more
Weighs more
Uses more consumables
Needs better power
There’s nothing wrong with owning a 50 amp plasma cutter.
Most Kiwi sheds are perfectly served by one.
You don’t need to prove anything to anyone with an 80 amp machine if you’re cutting 5mm plate.
My Simple Advice
Look at what you cut weekly.
Match the machine to that.
Then go one size above your normal thickness.
Not three sizes above.
Don’t buy for the story you tell your mates.
Buy for the jobs you actually do.
Final Answer
For most home users in New Zealand:
40–50 amp plasma cutter on 240V power
That comfortably covers 3–12mm steel.
Stop overthinking it.
Stop overspending.
Buy for your real work.
Not your imaginary work.