Square D QO340 - 40A, 3-Pole, Miniature Circuit Breaker (MCB)

The Square D QO340 40A, 3-Pole Miniature Circuit Breaker (MCB) brings dependable overcurrent protection to three-phase electrical systems in a compact, easy-to-integrate package. Designed for panelboards, switchboards, and control panels, this 40-amp MCB from the trusted Square D QO family helps keep critical equipment and wiring safe in demanding industrial, commercial, and OEM environments. Key specifications at a glance - Current rating: 40A - Poles: 3-Pole - Breaker type: Miniature Circuit Breaker (MCB) Why the QO340 stands out - Three-phase protection you can rely on: The 3-pole configuration is tailored for true 3-phase circuits, delivering coordinated interruption across all phases to prevent imbalanced loads and equipment damage. - Seamless integration with Square D QO-series panels: Built to slot into standard QO-series panelboards, switchboards, and control panels, minimizing compatibility concerns during upgrades or retrofits. - Purpose-built for demanding environments: The QO340 is engineered to provide quick, reliable protection in the distribution pathways of industrial and commercial settings, helping reduce downtime and protect motors, wiring, and control logic. - Practical, serviceable design: A straightforward replacement option within existing distribution schemes, supporting ongoing maintenance and reliable long-term operation. Ideal applications - Industrial distribution panels and motor control centers where robust 3-phase protection is essential - Commercial electrical rooms that rely on compact, dependable MCBs for modular protection - OEM equipment where a proven 40A, 3-pole protective device is required for safe, consistent operation What this means for you - Protects circuits from overloads and short circuits, helping to safeguard both people and equipment - Supports reliable operation of three-phase processes, reducing the risk of fault-induced downtime - Provides a clear, maintainable protection strategy within panelboards and control panels Installation and best-use tips - Confirm your enclosure and bus configuration are compatible with Square D QO-series MCBs - Ensure the circuit is loaded within the 40A rating and that the panel is designed for 3-pole protection - Follow local electrical codes and the manufacturer’s installation guidelines for terminal torque and wiring practices - Label circuits clearly after installation to support safe future maintenance and inspections With the Square D QO340, you’re choosing a trusted, purpose-built 40A, 3-pole MCB that delivers precise, reliable overcurrent protection for three-phase systems. It’s the practical, durable choice for safeguarding panelboards, switchboards, and control panels across industrial, commercial, and OEM applications.