Square D QO390 - 90 A, 240 V, 3-Pole Plug-In Circuit Breaker | AmpState

When you need dependable protection for 240V circuits, the Square D QO390 delivers precisely what you require. This 90A, 240V, 3-pole plug-in molded case circuit breaker is built for quick installation in panelboards and load centers, providing reliable overcurrent and short-circuit protection for residential, commercial, and light industrial applications.

What makes the QO390 stand out

• Fast plug-in connection: streamlined installation and painless replacement minimizes downtime during panel upgrades or servicing.
• Thermal-magnetic trip unit: provides stable, repeatable protection across loads and temperatures by combining thermal overload sensing with magnetic short-circuit detection.
• OEM-compatible compatibility: designed to work with matching Square D QO panelboards and load centers for a safe, code-compliant fit.
• Three-pole, 90A, 240V configuration: robust protection for 3-wire circuits and balanced loads in 240V systems, suitable for multi-pole applications.
• Plug-in mounting: drop-in style that simplifies installation and future servicing without lugs or bolts.

Technical snapshot

• Manufacturer: Square D
• Part Number: QO390
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 90A
• Voltage Rating: 240V
• Number of Poles: 3
• Mounting Style: Plug-in
• Application: Branch circuit overcurrent and short-circuit protection

Ideal use cases

• Residential panel upgrades and service panels needing reliable 90A protection on 240V circuits.
• Commercial panels in small to mid-size facilities requiring quick-replace, plug-in breakers for routine maintenance.
• Light industrial setups with multi-wire branch circuits where fast swap-in protection minimizes downtime.

The QO390 doesn’t just protect equipment—it helps keep your electrical system safe, compliant, and running smoothly. With a rapid plug-in connection, a dependable thermal-magnetic trip, and compatibility with Square D QO panelboards, it’s a practical, long-term choice for ongoing electrical reliability. Choose AmpState for genuine Square D components and prompt, knowledgeable support for your panel upgrades and replacements.