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North American NEMA and international IEC motors look similar and often do the same job — but the frames don’t bolt up, the ratings mean different things, and buying the wrong one costs weeks. Here’s the plain-English comparison.
| Attribute | NEMA (North America) | IEC (International) |
|---|---|---|
| Rating basis | Horsepower (HP) | Kilowatts (kW) |
| Frame sizes | NEMA MG1 (48, 56, 143T, 182T, etc) | IEC 60072 (63, 71, 80, 90, 100, 112, 132, 160, 180, 200, 225, 250, 280, 315) |
| Frame & mount interchange | Not interchangeable. Adapters exist for some C-face applications; foot-mount is generally incompatible. | |
| Voltage | 230/460V, 575V, 208V — 60 Hz | 230/400V, 400/690V — 50 Hz (60 Hz motors also common) |
| Efficiency ratings | NEMA Premium, EPAct standard, EISA | IE1, IE2, IE3, IE4, IE5 (increasingly efficient) |
| Enclosure codes | ODP, TEFC, TENV, XP | IP-rated (IP54, IP55, IP65, IP66, IP69K) |
| Where used | Canada, U.S., Mexico, parts of Latin America | Europe, Asia, most of Africa & South America, on imported machinery worldwide |
• Building or maintaining a North-American-designed system.
• Replacing an existing NEMA motor (frame must match).
• Working with a local system integrator using NEMA sizing.
• Application is on 60 Hz power (Canada / U.S. standard).
• Machine came from Europe / Asia and needs a like-for-like replacement.
• System documentation is in metric (kW, mm, IP-code).
• OEM-standard parts require IEC mount.
• Application is 50 Hz (though 60 Hz IEC motors are common).
We stock and support both — browse IEC options from Omnidrive or the full NEMA catalog from all major brands.
Frame sizes are the #1 blocker when swapping between standards. These are the closest matches — but always confirm shaft diameter, mounting hole spacing, and shaft height before you commit.
| NEMA Frame | IEC Frame (closest) | Shaft Height | Typical HP Range | Notes |
|---|---|---|---|---|
| 48 / 56 | 63 – 71 | 63–71 mm / 2.75–3.5″ | Fractional to 1 HP | Small fractional; often not directly interchangeable |
| 143T / 145T | 80 – 90S | 90 mm / 3.54″ | 1 – 2 HP | Shaft diameter differs (0.875″ NEMA vs 24 mm IEC) |
| 182T / 184T | 100L – 112M | 100–112 mm / 4.5″ | 3 – 5 HP | Common conversion size; adapters available |
| 213T / 215T | 132S – 132M | 132 mm / 5.25″ | 7.5 – 10 HP | Mounting hole spacing differs |
| 254T / 256T | 160M – 160L | 160 mm / 6.25″ | 15 – 20 HP | Popular industrial size; C-face adapters common |
| 284T / 286T | 180M – 180L | 180 mm / 7″ | 25 – 30 HP | Approximate; verify BA dimension |
| 324T / 326T | 200L | 200 mm / 8″ | 40 – 50 HP | — |
| 364T / 365T | 225S – 225M | 225 mm / 9″ | 60 – 75 HP | Larger frames get increasingly custom |
| 404T / 405T | 250M – 280S | 250–280 mm / 10″ | 100 – 125 HP | Special order territory |
| 444T / 445T | 280M – 315S | 280–315 mm / 11″ | 150 – 200 HP | Custom mounting almost always needed |
Full NEMA chart at NEMA Frame Sizes Reference. For exact IEC dimensions, ask us.
Frequency: Most modern IEC motors are dual-frequency (50/60 Hz). On 60 Hz, an IEC motor rated 400V/50Hz runs at 480V/60Hz — same slip, ~20% more speed, ~20% more HP. Check the nameplate carefully.
Voltage: 400V IEC motors work on 460V NEMA power if the nameplate lists both. 690V IEC motors are rare in Canada — special order.
Verdict: Usually works, but always spec dual-voltage/dual-frequency for peace of mind.
Frequency: 60 Hz NEMA motor on 50 Hz power runs 17% slower and can overheat if loaded to nameplate HP. Not recommended without VFD.
Voltage: 460V/60Hz NEMA motor on 400V/50Hz will run — but under-voltage plus wrong frequency stacks two problems.
Verdict: Better to source a local IEC motor or use a VFD for frequency conversion.
Rebate programs, tender specs, and OEM requirements often cite one standard but not the other. Here’s the mapping.
| NEMA (North America) | IEC IE Class | Meaning | Regulatory Status |
|---|---|---|---|
| — | IE1 (Standard) | Baseline efficiency; obsolete in most markets | Banned for new industrial in EU (2011), Canada (2010) |
| EPAct (1997) | IE2 (High) | Old NA minimum standard | Superseded by EISA in NA; still legal in some markets |
| NEMA Premium / EISA | IE3 (Premium) | Current NA minimum; global industrial standard | Required by EISA (2010) in Canada + U.S. |
| NEMA Super Premium | IE4 (Super Premium) | Beyond legal minimum; ~2-3% higher than IE3 | Voluntary; rebate programs favor this |
| — | IE5 (Ultra Premium) | Emerging class; typically PM or synchronous reluctance | Not yet mandated; specialized applications |
All Baldor, WEG, Marathon, US Motors ship as NEMA Premium (IE3) minimum in Canada. Ask about IE4/Super Premium for high-runtime applications — the efficiency calculator shows payback.
If replacing an existing motor, always match the existing standard. NEMA in, NEMA out. IEC in, IEC out. Cross-swapping requires mounting rework.
Building in Canada / U.S.? Default to NEMA. Local availability, standard voltages, familiar to your electricians. Only go IEC if metric hardware surrounds it.
Machine came from Europe / Asia? Default to IEC. The rest of the equipment (guards, gearbox, controls) is metric — keeping the motor metric avoids adapter chains.
| Factor | NEMA in Canada | IEC in Canada |
|---|---|---|
| Availability | Thousands of SKUs from every major brand, in-stock | More limited — Omnidrive and select WEG lines; some special order |
| Lead time (standard sizes) | Same-day to 2 days | 2 days to 2 weeks (varies by brand) |
| Price | Competitive across brands | Often 10–25% more due to import + smaller volume |
| Parts & service | Local service centers for every major NEMA brand | Sparser service network; some parts special order |
| Warranty support | Standard 1–3 year, local claim handling | Standard 1–2 year; claims may go through local distributor |
HP and kW are ratings, but the motor’s speed, torque curve, and starting behaviour depend on frequency. A 5 HP NEMA at 60 Hz and a 3.7 kW IEC at 50 Hz are NOT the same motor.
Adapters solve mounting bolt patterns but don’t solve shaft diameter, key size, shaft length, or overall footprint. Order the correct motor OR plan a full retrofit.
Not inherently. NEMA Premium = IE3, and both go up to IE4/IE5. Buy for efficiency class, not standard.
Close but not identical. TEFC = totally enclosed fan cooled (NEMA definition). IP55 = protected against dust and water jets (IEC definition). Most industrial motors satisfy both, but some don’t.
Yes — Class A, B, F, H are shared. Both standards recognize 105°C (A), 130°C (B), 155°C (F), and 180°C (H) as the maximum winding temperatures.
Yes — VFDs care about voltage, current, and frequency, not the motor’s frame standard. Set your VFD to the motor’s nameplate values (kW, base frequency, current) and it’ll drive fine.
Short-term: an adapter plate + custom shaft coupling can bridge the gap. Long-term: source the correct IEC replacement. We keep IEC in stock for common sizes — ask before you improvise.
Not particularly. Quebec industry still runs predominantly NEMA (60 Hz, 460/575V). IEC shows up on European-imported equipment across every province.
Nameplate is the fastest way — frame code (143T = NEMA, 90S = IEC), HP vs kW as the primary rating, and voltage (460/575V typically NEMA, 400V typically IEC). Physical clues: IEC motors often have taller narrower housings and metric bolt heads.
Send us a photo of the existing nameplate + the mounting arrangement. We’ll spec the correct standard and part number.
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