The Castair 15-254-3 is a 15 HP three-phase open drip proof motor rated for 208/230/460V service, built specifically for industrial air compressor duty. This is the OEM replacement motor for Castair industrial systems in the 15 HP class running on three-phase power. The 254T NEMA frame, 1725 RPM, and 1-3/8 inch shaft are the defining specs — confirm all three match your existing installation before ordering. Weight is 255 lbs, so plan your installation accordingly.
Motor Specifications
- Horsepower: 15 HP
- Phase: 3-Phase
- Voltage: 208/230/460V (dual-voltage winding)
- Service Factor: 1.15
- Amp Draw: 41A at 208V / 40A at 230V / 20A at 460V
- Frame: 254T NEMA frame
- RPM: 1725
- Shaft Size: 1-3/8 inch
- Weight: 255 lbs
- Listings: UL and CSA listed
- Enclosure: Open Drip Proof (ODP)
- Part Number: 15-254-3
Frame Compatibility: 254T vs. Adjacent Sizes
The 254T frame is specific to 15 HP class motors — it is not interchangeable with the 215T frame used on 7.5-10 HP motors, nor with the 256T frame used on 20 HP motors. The mounting bolt pattern, shaft height, and overall dimensions are different. If you are replacing a motor on an existing Castair 15 HP unit, verify the frame designation on the motor nameplate before ordering. Substituting a different frame requires replacing the motor base, which is a significant additional cost and labor investment.
Castair Motor Base for 15 HP
- Loose base: 254D adjustable belt tensioner base
- Pre-mounted base: 254DM (motor pre-mounted to the tensioner base)
- For duplex 15 HP installations, order two 254D or 254DM bases — one per pump
Three-Phase Advantages at 15 HP
At 15 HP, the advantages of three-phase over single-phase become more pronounced. A 15 HP single-phase motor (if available) would draw approximately 75-80 amps on a 230V circuit — requiring very heavy wire, a large dedicated breaker, and a substantial load on your utility service. The 15-254-3 draws only 20A at 460V, cutting infrastructure costs dramatically. For any shop running 15 HP or above, three-phase power is the only practical choice for new installations.
Dual Voltage Wiring
- 460V (preferred): 20A draw — standard wire sizing handles this easily, lower line losses
- 208/230V: 41/40A draw — substantially heavier wiring required. Use 460V if available.
- Motor is internally reconnectable at the terminal board in the conduit box. Confirm voltage with your electrician before wiring.
Compatible Compressor Pumps
Castair 15 HP three-phase systems typically use the C3 or C3G pump. The C3 is a two-stage, W3 cylinder configuration weighing 485 lbs with a 20.7" flywheel and 1-gallon oil capacity. The C3G uses a different flywheel (14-3B) and holds 1.75 gallons. Both run at approximately 570 RPM at the pump in standard configurations, producing high-pressure, high-volume output for heavy industrial use.
What's in the Box
- 1x Castair 15 HP open drip proof motor, 208/230/460V 3-phase, Frame 254T, 1725 RPM
- Standard motor leads and terminal connections
Note: Motor base (254D/254DM), pulleys, belts, and belt guard sold separately. A magnetic motor starter is required for three-phase applications.
When Does a Shop Need This vs. Stepping Up or Down
- Step down to 10 HP (10-215-3): If your actual air demand is 35 CFM or less at 175 PSI, the 10 HP system may be sufficient and significantly cheaper to install and operate
- This motor (15 HP, $1,677.14): Right for shops running continuous duty at 40+ CFM, production environments, or multi-bay automotive shops with simultaneous high-demand tools
- Step up to 20 HP (20-256-3): When 15 HP cannot keep up with demand or when you are sizing for future expansion
If you are unsure whether 15 HP is right for your application, call us. We can help you calculate CFM requirements based on the tools you run and the duty cycle you need.
Why Buy From Air Compressor Factory Direct?
We have been specializing in industrial air compressor components since 2016. We stock Castair motors in the full range from 2 HP to 30 HP, and we can help confirm the correct replacement for your unit. Free shipping, free technical support at 866-217-0063, and full manufacturer warranty on all Castair components.
Call 866-217-0063 for quick answers and help!
