Square D QOB390 - 90 A, 240 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Meet the Square D QOB390 — a 90 A, 240 V, 3-pole bolt-on molded case circuit breaker designed to deliver dependable branch circuit overcurrent and short-circuit protection in panelboards and load centers. Built for consistent performance in residential, commercial, and light industrial environments, it combines robust mounting with precise protection.

• Secure bolt-on mounting for a rigid, vibration-resistant bus connection that stays aligned under demanding conditions.
• Thermal-magnetic trip unit provides stable, repeatable protection across a wide range of fault scenarios, reducing nuisance trips and preserving downstream circuitry.
• 3-pole design ensures balanced protection and coordinated tripping across all phases for shared loads and multi-wire circuits.
• 90 A, 240 V rating targets branch circuits that demand higher protection without compromising system accessibility or expandability.
• OEM compatibility with matching Square D panels and load centers, helping maintain performance, reliability, and ease of replacement.

Technical snapshot

• Manufacturer: Square D
• Part Number: QOB390
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 90 A
• Voltage Rating: 240 V
• Number of Poles: 3
• Mounting Style: Bolt-on

Ideal applications

• Protection for branch circuits in residential, commercial, and light industrial panelboards and load centers.
• Upgrading or replacing aging breakers where a secure, vibration-resistant connection is critical.
• Systems where consistent thermal-magnetic protection minimizes nuisance trips during startup surges or varying load conditions.

Why this breaker stands out

• Durable bolt-on mounting reduces movement and wear in environments with vibration or mechanical stress.
• Thermal-magnetic trip provides reliable coordination between overload protection and short-circuit protection, helping protect both equipment and occupants.
• OEM compatibility means straightforward installation in compatible panels, preserving the intended electrical performance and simplifying maintenance.

If you’re designing or retrofitting a panel system, the Square D QOB390 delivers the rugged, reliable protection you need for demanding 90 A circuits. It’s a practical choice for technicians seeking a proven, easy-to-integrate solution that aligns with Square D panelboards and load centers while delivering care-free operation in everyday use.