Here's What You're Really Asking
When people call us asking "can I convert 240V to 3-phase," they usually have one of these situations:
"I've got 240V at my shop..."
You have standard 240V single-phase service (like most residential and light commercial buildings) and you bought equipment that needs 3-phase. This is the most common scenario we deal with.
"My machine says 240V 3-phase..."
The nameplate on your equipment shows 240V 3-phase (sometimes written as 230V or 220V — same thing). You need that specific voltage and phase configuration.
Good news either way: a phase converter handles both situations. You feed it 240V single-phase, and it outputs 240V three-phase.
240V Single-Phase vs. 240V Three-Phase
These get confused a lot because they're both "240 volts." But they're not interchangeable. Here's the difference:
| Characteristic | 240V Single-Phase | 240V Three-Phase |
|---|---|---|
| Hot Wires | 2 (L1, L2) | 3 (L1, L2, L3) |
| Voltage Between Hots | 240V | 240V (each pair) |
| Phase Relationship | 180° apart | 120° apart |
| Power Delivery | Pulsing (gaps) | Constant (smooth) |
| Common Use | Homes, small shops | Industrial equipment |
| Available at Your Location | ✓ Probably yes | Probably no (that's why you're here) |
Your equipment needs that third phase because industrial motors are designed for it. Three-phase power is smoother — there are no "dead spots" in the power cycle — so motors run cooler, quieter, and last longer.
How the Conversion Works
A rotary phase converter doesn't just "convert" your power — it actually generates the missing third phase. Here's what happens inside:
240V Single-Phase Goes In
Your two hot legs (L1 and L2) from your panel connect to the converter's input. Same 240V you'd use for a dryer or welder outlet.
The Idler Motor Spins Up
Inside the converter is a three-phase motor running as a generator. Start capacitors kick it into rotation on your single-phase power.
Third Phase Gets Generated
As the idler motor spins, electromagnetic induction creates a third phase of electricity (L3). This is real generated power, not a trick.
240V Three-Phase Comes Out
Now you've got three hot legs, 120° apart, each pair measuring 240V. Your equipment can't tell the difference from utility three-phase.
What If My Equipment Needs 480V?
Some industrial equipment — especially larger CNCs and machinery from commercial shops — runs on 480V three-phase. If that's your situation, you've still got options:
Option 1: Dual-Voltage Converter
Some Phoenix converters include a step-up transformer that takes 240V single-phase in and provides both 240V and 480V three-phase outputs. One unit, both voltages.
Option 2: Separate Transformer
Run a standard 240V converter, then add a step-up transformer on the output side. More components, but offers the flexibility you want to add more 480V equipment later.
⚡ Quick Check
Check your machine nameplate before assuming that you will need 480V. Many industrial machines are dual-voltage machines (240V/480V) and only require a change in internal wiring. This may be an effective way to reduce your costs and complications.
What Size Converter Do You Need?
This is where people sometimes get tripped up. Here's the straightforward approach:
For a single machine: Match the converter to your motor's horsepower. 10HP machine = 10HP converter minimum.
For CNC equipment: Go 25-50% larger than the spindle motor rating. CNCs have servo motors and electronics that create extra demand, especially on startup.
For multiple machines: Add up the horsepower of everything that might run simultaneously. If you have a 5HP mill and a 3HP lathe that you might run at the same time, you need at least an 8HP converter.
Not sure? Call us with your equipment list. We do this every day and we'll tell you exactly what size you need — no guessing, no overselling.
Common Questions
Is converted 3-phase as good as utility 3-phase?
From a properly sized rotary converter? Yes. Your equipment can't tell the difference. The third phase is real generated electricity, and when the converter is sized correctly, the voltage balance is within spec. We've got customers running Haas and Mazak CNCs on our converters with zero issues.
Will this work with my specific machine?
If your machine has a standard three-phase motor, yes. This includes mills, lathes, surface grinders, CNCs, air compressors, welders, dust collectors — pretty much anything with a 3-phase motor. The exceptions are very specialized equipment with unusual power requirements, which is rare.
Do I need an electrician to install it?
If you're comfortable with 240V electrical work, you can do it yourself — it's connecting wires to terminals, not brain surgery. That said, if you're not confident working with electricity, hire an electrician. Should take them a few hours at most. We include detailed installation instructions.
What about VFDs? Can I use a phase converter with a VFD?
Rotary phase converters work great with VFD-controlled equipment — that's actually a common setup for CNC machines. Digital/electronic phase converters are the ones that have problems with VFDs. Stick with rotary and you're good.
How much power do I need from my panel?
The converter draws roughly 1.5x the connected load in single-phase amps. So a 10HP load (about 28 amps at 240V three-phase) will draw around 42 amps single-phase from your panel. Make sure your panel and breaker can handle it. We can help you calculate this.
Ready to Get Your Equipment Running?
Tell us what machine you're trying to power. We'll recommend the right converter — no upselling, no BS.