Square D | 999390 | Circuit Breaker | 90A | 3-Pole | 600V | 10kA | Bolt-On

Square D 999390 Circuit Breaker is a rugged bolt-on solution designed for demanding 600V systems. With a 90A rating across 3 poles, this unit provides dependable, three‑phase protection for industrial and commercial panels, retrofit projects, and replacement scenarios where exact specifications matter. The 10kA interrupt rating adds a robust margin for fault clearance, helping keep your electrical system safer and more reliable.

Why this Square D 999390 stands out

• Bolt-On installation for secure, durable mounting in compatible panels, reducing the risk of loose connections that can cause nuisance trips.
• Three-pole design delivers synchronized protection across all three phases, essential for balanced load and equipment safety in 3‑phase circuits.
• 600V capacity matches a wide range of commercial and industrial applications, supporting robust protection where higher voltage service is required.
• 10kA interrupt rating provides strong fault current clearance, helping minimize arc energy during faults and protecting equipment and personnel.
• Spec-for-spec replacement ideal for maintenance, retrofit, and replacement projects that require exact compatibility with existing gear.

Specs at a glance

• Amperage: 90A
• Poles: 3-Pole
• Voltage: 600V
• Interrupt Rating: 10kA
• Mounting: Bolt-On
• Part/Model: 999390

Ideal use cases and practical applications

This circuit breaker excels in situations where you need a precise, high‑integrity protective device that aligns with existing equipment. It’s well-suited for:

• Maintenance and retrofit projects where the goal is to match the original specifications exactly.
• Replacement of failed or worn-out breakers in 3‑phase, 600V systems.
• Industrial or commercial panels requiring reliable 90A protection with a strong interrupt rating.

How it compares and why it matters

Compared to other mounting styles, the bolt-on design of the Square D 999390 provides a physically secure and mechanically robust connection, which can improve reliability in environments with vibration or frequent service. Its 3‑pole arrangement ensures that all phases trip together, reducing the risk of unbalanced loads and protecting equipment from uneven current that can lead to damage over time.

Important compatibility notes

Before you order, confirm fit and ratings for your panel. The part number 999390 is the most reliable reference for compatibility, so use it as your primary check when sourcing replacements or upgrades.

Buying with confidence: this breaker is designed for precise alignment with Square D panels and related equipment that specify bolt-on, 3‑pole, 90A, 600V, 10kA devices. If your project calls for exact specs and durable, field-reliable protection, the 999390 is built to meet those demands.