Can I run my CNC and my air compressor on the same phase converter?

Yes, if sized correctly. The CNC spindle plus a 7.5 HP compressor on the same converter requires sizing to the combined startup load. AutoStart is often recommended — the converter sleeps when neither machine is running.

Can I use a static phase converter for a small CNC?

No. Static converters only deliver 2/3 of the motor's rated HP, causing spindle stalls and servo undervoltage. Always use a rotary on a CNC regardless of HP.

Phase Converters for CNC Machines

Q: Will my Haas/Tormach/Mazak/Fanuc CNC throw phase-loss alarms on a rotary converter?

Not on a Phoenix. Phase-loss alarms happen when leg-to-leg imbalance exceeds the CNC controller's tolerance (usually 6–8%). Phoenix's Precision Balanced output stays inside 3% under load, which is well within every major controller's spec.

Q: How do I run a 460V CNC on single-phase 230V utility?

Use a Phoenix Phase Converter + Transformer Package. The converter creates three-phase 230V; the integrated transformer steps it up to 460V. Built as one matched unit, one enclosure, one warranty.

Why CNCs are different

A CNC isn't a single motor. It's a spindle motor, servo drives, coolant pumps, chip conveyors, tool changers, and a controller all sharing one three-phase feed. Each component has different inrush characteristics, and the VFD-driven spindle is sensitive to voltage imbalance in a way a simple induction motor isn't.

Most "cheap" phase converters produce 8–12% voltage imbalance leg-to-leg under load. Run a Haas controller on that and you'll see spindle alarms, servo faults, axis-stalls, and "phase loss" errors — even though all three phases are present. The CNC isn't lying. It's protecting itself from dirty power.

Phoenix's Precision Balanced output stays within 3% leg-to-leg under load. That's the headroom Haas, Tormach, Fanuc, Mazak, and Siemens recommend in their installation guides. Your CNC stops faulting because the power finally meets the spec.

How to size a phase converter for your CNC

Look at the nameplate of your CNC's largest single motor — usually the spindle. Add 50% headroom to handle hard-start conditions (tap cycles, rigid tapping, heavy roughing passes). That's your minimum Phoenix HP.

Quick CNC sizing reference

CNC Class	Typical Spindle HP	Recommended Phoenix Unit
Hobby / desktop (Tormach 440, PCNC 440)	1–3 HP	5 HP Phoenix
Small benchtop mill (Tormach 770, Haas TM-0)	3–5 HP	7.5 HP Phoenix
Production VMC (Haas Mini Mill, TM-1)	5–7.5 HP	10–15 HP Phoenix
Mid-size VMC (Haas VF-2, VF-3, Mazak QT-Nexus)	10–15 HP	20–25 HP Phoenix
Full-size VMC / HMC (Haas VF-4, VF-5, Mazak VTC-300)	15–25 HP	30–40 HP Phoenix
Large CNC lathe / 5-axis (Mazak Integrex, Haas EC-500)	25–40 HP	50–60 HP Phoenix

If you're running multiple CNCs off one converter, size to the simultaneous combined load, not the sum of all nameplates. Most shops never run every machine at peak at once.

Cory in Youngstown, Ohio — 30 HP Haas CNC mill

Manufacturing · 30 HP load · Phoenix 60 HP Standard Rotary

Cory had a 30 HP Haas mill, single-phase 230V utility service, and a quote from a local electrician for $24,000 to bring in three-phase. He called us instead. We sized him a 60 HP Phoenix Standard Rotary to handle the Haas spindle plus the auxiliaries with full 50% headroom, shipped it freight to Youngstown, and his electrician had it wired in over a weekend. Cory's been running the Haas on single-phase power ever since.

Total investment: a small fraction of the utility quote. Time saved: weeks waiting on the utility schedule.

CNC brands and models we power every day

Vertical Machining Centers (VMCs)

Haas — Mini Mill, TM-1, TM-2, TM-3, VF-1 through VF-5, VF-6, Super Mini Mill, EC-400, EC-500
Tormach — PCNC 440, PCNC 770, 1100M, 1100MX, 24R, 8L Lathe
Mazak — VTC-200, VTC-300, VCN-510C, Integrex i-series
Bridgeport — Series I CNC retrofits, Romi, BOSS, Hardinge GX series
Fadal, Fanuc Robodrill, Brother Speedio, Doosan, Hyundai-Wia, Hwacheon

CNC Lathes

Haas — TL-1, TL-2, ST-10, ST-15, ST-20, ST-30
Mazak — QT-Nexus, QT-Compact, Hyper Quadrex
Mori Seiki, Okuma, Doosan Puma, Hyundai HiT, Romi C series

CNC Routers & Plasma

ShopBot PRSalpha, ShopBot Buddy, CAMaster, Laguna IQ, MultiCam, Thermwood
Hypertherm Powermax 105/125 (with proper isolation), AVANI/Vicon CNC plasma tables

Not seeing your machine? We've sized converters for every CNC made in the last 30 years. Call us at 800-417-6568 with your spindle HP and we'll size it.

What about VFDs and rotary phase converters together?

Best question we get. Yes — Phoenix's Precision Balanced output works with every modern VFD because the balance is tight enough that the VFD's input rectifier sees what it expects. We have customers running:

Haas controllers with Yaskawa-driven spindles
Tormach PathPilot with PowerFlex VFDs
Hurco controllers with Allen-Bradley drives
Fanuc 30i / 31i / Robodrills

The 3% leg-to-leg balance is the magic number. Cheap converters can't hold it. Phoenix does, under load, every cycle.

CNC-specific questions

Will my Haas/Tormach/Mazak/Fanuc CNC throw phase-loss alarms on a rotary converter?

Not on a Phoenix. The alarms you've heard about happen when leg-to-leg imbalance exceeds the CNC controller's tolerance (usually 6–8%). Phoenix's Precision Balanced output stays inside 3% under load, which is well within every major controller's spec. We have hundreds of CNC customers running for years without a single phase-loss fault.

Can I run my CNC and my air compressor on the same converter?

Yes, if you size for it. The CNC spindle plus a 7.5 HP compressor on the same converter requires sizing to the combined startup load. We typically recommend AutoStart for this setup — the converter sleeps when neither machine is running, then wakes for whichever calls for power first. Saves you 4–8 kWh per workday on standby load alone.

Do I need DualZone for a CNC?

Usually no. DualZone is for hard-starting loads like large air compressors and grain dryers that draw 6× nameplate at startup. CNC spindles ramp up under VFD control, so they're soft-starting from the converter's perspective. Standard Rotary or AutoStart is the right call for almost every CNC application.

I have a 5 HP CNC. Can I just use a static converter?

Don't. Static converters only deliver 2/3 of the motor's rated HP because the third phase is missing under load. On a CNC that means your spindle stalls in heavier cuts and your servos see undervoltage. Always use a rotary on a CNC, regardless of HP.

What about three-phase 460V CNCs?

If you have single-phase 230V incoming and a 460V CNC, you need a Phoenix Phase Converter + Transformer Package — we build them as a matched unit. The converter creates three-phase 230V; the integrated transformer steps it up to 460V. One enclosure, one warranty, sized as a system. See our Phase Converter & Transformer Packages.

How loud is a rotary phase converter next to a CNC?

Quieter than your CNC. Phoenix's TEFC cast-iron idler motor runs at roughly 60 dB at three feet — about the same as conversational speech. Most shops put the converter in a utility room or against an outside wall and never think about it again.

Ready to size a Phoenix for your CNC?

One call to one engineer. We'll ask your CNC model and your largest motor HP, then quote the exact unit that fits. No automated menu, no upsell, no guessing.

📞 Call 800-417-6568 Sizing Calculator →

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