Square D QOU340 - 40 A, 240 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Square D QOU340 is a 40 A, 240 V, 3-pole bolt-on molded case circuit breaker engineered to deliver reliable branch-circuit overcurrent and short-circuit protection in panelboards and load centers. Built for environments where vibration or periodic maintenance is a concern, this unit combines strong mechanical mounting with precise electrical protection to keep critical electrical systems safe and up to code.

• Secure bolt-on mounting provides a rigid, vibration-resistant bus connection in panels, minimizing loosening risks and ensuring consistent electrical contact even in demanding installations.
• Thermal-magnetic trip unit delivers stable, repeatable protection: the thermal element handles sustained overloads, while the magnetic element responds rapidly to short circuits, reducing the chance of damage to downstream equipment.
• OEM compatibility is designed to work with matching Square D load centers and panelboards, helping you maintain system architecture and warranty assurances without sacrificing performance.
• Versatile for multiple sectors suited for residential, commercial, and light industrial applications where 3-phase or 2/3-wire configurations require reliable 40 A protection at 240 V.

Ideal use scenarios include protecting motor loads, lighting circuits, HVAC equipment, pumps, and other branch circuits in service panels or subpanels. When upgrading aging panels or expanding capacity, the QOU340 offers a drop-in solution that preserves electrical integrity and minimizes downtime thanks to its rugged bolt-on design and predictable trip behavior.

Technical snapshot

• Type: Thermal-magnetic molded case circuit breaker
• Amperage rating: 40 A
• Voltage rating: 240 V
• Number of poles: 3
• Mounting style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Choosing the Square D QOU340 means prioritizing dependable protection, straightforward installation, and compatibility with your existing Square D infrastructure. For technicians and electricians, it’s a practical, long-term investment in panel reliability and safety across residential, commercial, and light industrial environments.