Capacitor Start/Induction Run Submersible Motor Control, 3/4 hp

Myers SMC-IR0721-01 – STA-RITE/Pentek 3/4 HP Submersible Motor Control Box, NEMA 3R

The Myers SMC-IR0721-01 submersible motor control box is designed for use with 3-wire, 3/4 HP, 230V single-phase submersible pump motors. This control unit includes components required to initiate motor startup and manage overload protection. Built to meet demanding well pump and water system requirements, the control is compatible with Pentek and STA-RITE motors and conforms to field standards for residential, agricultural, and light commercial applications.

It features a fully enclosed NEMA 3R-rated steel cabinet, making it suitable for both indoor and outdoor installations. With durable internal components, this unit is engineered to deliver consistent electrical performance and mechanical reliability in standard pump system environments.

Component Features

• ✅ NEMA 3R Enclosure – Galvanized steel housing with rain-tight design, suitable for outdoor wall or pedestal mounting.
• ✅ HardBond™ Powder-Coated Finish – Enhanced corrosion resistance, providing extended life in high-humidity or coastal installations.
• ✅ High-Capacity Starting Relay – Factory-calibrated relay ensures correct phase sequencing and motor start-up under load.
• ✅ Manual Reset Overload Protection – External push-button reset avoids cover removal for thermal trips.
• ✅ Heavy-Duty Terminal Lugs – Accepts conductors up to #4 AWG for reduced voltage drop in long-run applications.
• ✅ Multiple Knockouts – Top and bottom conduit knockouts for versatile routing of supply and motor leads.
• ✅ Clear Internal Labeling – Includes factory-applied wiring schematic and terminal diagram for field reference.

Technical Specifications

• Motor Compatibility: 3/4 HP, 230V, 3-wire, single-phase submersible motors
• Frequency: 60 Hz
• Enclosure Rating: NEMA Type 3R
• Cabinet Dimensions: 4.9" W × 2.8" D × 8.5" H
• Mounting: Surface wall mount
• Warranty: Limited 1-Year Manufacturer Warranty

Installation Considerations

This motor control box is intended for fixed-location mounting near the pressure switch or disconnect. Installation should be performed by a licensed contractor familiar with NEC Article 430 and local code provisions related to motor circuit conductors and overcurrent protection. Field wiring must include proper conduit sealing and grounding in compliance with UL requirements.

The control box must be matched to motor horsepower and voltage. Improper sizing or incompatible component replacement can result in nuisance tripping or damage to pump windings. Always confirm model-to-motor compatibility during service or retrofit work.

Application Scope

Appropriate for submersible pump installations in wells, cisterns, and pressure-boosted water systems using 3-wire motors. Commonly used in residential water supply, agricultural irrigation, livestock watering, and off-grid tank fill systems where reliable motor control is required.

Component Summary

• ✅ Galvanized steel enclosure with powder-coated finish
• ✅ High-current starting relay with arc-resistant contacts
• ✅ Manual reset thermal protector accessible without opening cover
• ✅ Heavy-duty line and motor terminal blocks with screw compression

Contractor Notes

All connections should be torqued per label specs using approved lugs or ferrules. Ensure compatibility with pump curve and system pressure requirements. Avoid exposure to direct spray or standing water at outdoor locations—elevate box as required. Inspect relay contacts annually in high-duty-cycle environments or where voltage fluctuations are present.