Castair 7-184-1H Electric Motor — 7.5 HP, Single Phase, 3450 RPM, Frame 184T
The Castair 7-184-1H is a 7.5 horsepower single-phase electric motor built specifically for Cast Air industrial air compressors. It runs at 3450 RPM — the high-speed configuration in the Castair motor lineup — on a 184T NEMA frame. This motor is rated Open Drip Proof (ODP), UL and CSA listed, and carries a 1.15 service factor. It accepts 208/230V single-phase power and draws 34 amps at 208V or 31 amps at 230V.
Understanding where this motor fits in the Castair lineup is important before you order. Cast Air offers three 7.5HP single-phase motors:
- 7-184-1H (this motor): 7.5HP, 3450 RPM, 184T frame, 7/8" shaft. High-speed configuration.
- 7-215-1: 7.5HP, 1725 RPM, 215T frame, 1-3/8" shaft. Slow-speed, larger frame, 145 lbs.
The 3450 RPM speed of the 7-184-1H makes it the correct choice for direct-drive compressor configurations and belt-drive setups where the pulley ratio is designed around a high-speed motor. If your compressor is designed for a 1725 RPM motor, do not substitute the 7-184-1H — the RPM mismatch will over-speed the pump and shorten its life. Call us if you are unsure which speed is correct for your application.
Full Motor Specifications
- Part Number: 7-184-1H
- Horsepower: 7.5 HP
- Phase: Single phase
- Voltage: 208/230V
- Amperage: 34A at 208V / 31A at 230V
- RPM: 3450 (high-speed)
- NEMA Frame: 184T
- Shaft Diameter: 7/8"
- Service Factor: 1.15
- Enclosure: Open Drip Proof (ODP)
- Certifications: UL listed, CSA listed
- Weight: 95 lbs
What the Specs Mean for Your Application
RPM: 3450 — High Speed Configuration
The 3450 RPM operating speed defines this motor's application. Cast Air compressor pumps are designed to run at specific RPM ranges — typically 600–900 RPM at the pump for their cast iron industrial models. To get from 3450 motor RPM to the correct pump RPM, you need a belt-drive system with an appropriate pulley ratio. A 3450 RPM motor requires a larger reduction ratio than a 1725 RPM motor to achieve the same pump speed. Verify that your compressor's existing pulley and belt configuration is matched to a 3450 RPM drive before ordering this motor. If you are replacing a motor and the original was 3450 RPM, the 7-184-1H is the correct replacement. If the original was 1725 RPM, order the 7-215-1 instead.
Frame 184T — Compact High-Speed Frame
The 184T NEMA frame is smaller and lighter than the 215T frame used on the slower 7.5HP models. At 95 lbs, the 7-184-1H is 50 lbs lighter than the 7-215-1 (145 lbs) and fits in more confined compressor cabinets. The T designation indicates a C-face or standard footprint with standardized shaft height, which ensures drop-in compatibility with 184T motor mounts. The 7/8" shaft diameter is appropriate for standard 184T sheaves and couplings.
Service Factor 1.15
A 1.15 service factor means this motor can sustain 1.15 times its nameplate load (8.6 HP continuous) without damage under normal ambient conditions. On a compressor, this provides headroom for the inrush current spike at startup and for elevated loads during high-pressure operation near the pump cut-out. It is not a license to run the motor at 115% load continuously — it is a safety margin for the transient demands of compressor operation.
Single Phase Power Draw — What to Expect at the Panel
At 208V, this motor draws 34 amps full load. At 230V, it draws 31 amps. For a 7.5HP single-phase motor, the startup inrush current is typically 6 to 8 times the full-load amperage — meaning you should expect 186–272 amps of inrush at the moment of startup. Your circuit breaker, wiring, and magnetic starter must be sized for this inrush, not just the running current. Standard practice is to size the breaker at 175–250% of full-load amperage for motor circuits. For this motor at 230V (31A FLA), that means a 60–80 amp breaker minimum. Consult with your electrician and verify your panel capacity before installing a 7.5HP single-phase motor — single-phase draw at this power level is substantial.
Open Drip Proof Enclosure — Shop Environment Considerations
ODP motors are designed for indoor installation where they are protected from direct water spray and large debris, but they are not sealed against dust or fine particulates. In a clean machine room or compressor room, ODP is the correct and most cost-effective choice — the open ventilation keeps the motor cooler than a TEFC (Totally Enclosed Fan Cooled) motor, which extends winding life. If your compressor is in a very dusty environment — a woodshop, a grinding bay, a facility with heavy airborne debris — consider your mounting location carefully. Position the motor air intakes away from the primary dust source and replace the ODP motor with a TEFC if the environment is severe.
Castair Motor Lineup — Placing This Motor in Context
Castair offers motors from 2HP to 30HP to cover their full compressor lineup. The single-phase motors top out at 10HP (10-215-1). Three-phase options extend to 30HP. Within the 7.5HP single-phase options:
- 7-184-1H: 7.5HP, 1Ph, 208/230V, 3450 RPM, 184T frame, 7/8" shaft, 95 lbs — this motor
- 7-215-1: 7.5HP, 1Ph, 208/230V, 1725 RPM, 215T frame, 1-3/8" shaft, 145 lbs — slow-speed, larger frame
If you are stepping up from a smaller compressor, the 5HP single-phase motor (5-56Z-1H, 184T frame, 3450 RPM) is the next step down. If three-phase power is available at your facility, the 7-213-3 (7.5HP, 3Ph, 208/230/460V, 1725 RPM, 213T frame) is a more efficient option — three-phase motors run cooler, start more smoothly, and have lower inrush current than equivalent single-phase motors.
Replacement and Compatibility
This motor is the direct OEM replacement for Cast Air compressors shipped with the 7-184-1H motor. Verify the following before ordering:
- Shaft diameter: 7/8" — confirm your existing sheave or coupling is bored for 7/8".
- Frame mounting: 184T — confirm your motor mount and base are drilled for 184T bolt pattern.
- Rotation: Confirm required shaft rotation direction. Most compressor applications can be wired for either direction, but verify before installation.
- Voltage: Confirm 208V or 230V single-phase is available at the installation point. This motor is not dual-voltage in the sense of 115/230 — it is 208/230V only.
Why Buy From Air Compressor Factory Direct?
- Cast Air specialists: We know the motor lineup and which motor goes with which compressor model. If you give us your compressor model number, we can confirm whether the 7-184-1H is the correct replacement before you order.
- Free shipping on qualifying orders.
- Free technical support: Call 866-217-0063. Questions about wiring, sizing your breaker, or confirming sheave compatibility — we can help.
- Genuine Cast Air motors: OEM motors, not generic replacements. UL and CSA listed, correct frame dimensions, correct shaft size.
- Honest guidance: If the 7-184-1H is not the right motor for your application — wrong RPM, wrong frame, wrong phase — we will tell you and point you to the correct unit.
Call 866-217-0063 for quick answers and help!
