Square D QOB140 - 40 A, 120 V, 1-Pole Bolt-On Circuit Breaker | AmpState

Protect and streamline your electrical panel with the Square D QOB140 40A, 120V, 1-Pole Bolt-On Molded Case Circuit Breaker. Built for dependable branch-circuit overcurrent and short-circuit protection, this breaker is engineered to stay securely in place in panelboards and load centers, even in vibration-prone environments.

• Bolt-on mounting for a rigid, vibration-resistant bus connection that maintains a solid electrical path and reduces loosening over time.
• Thermal-magnetic trip unit delivers stable, repeatable protection: the thermal element handles gradual overloads, while the magnetic element responds rapidly to short circuits for fast isolation.
• OEM-compatible design engineered to pair with matching Square D OEM load centers and panelboards for a true plug-and-play installation with fewer compatibility concerns.
• Versatile applications suitable for residential, commercial, and light industrial environments where reliable 120V single-pole protection is required.

Use cases you’ll appreciate:

• Replacing a failed breaker in compatible Square D panelboards where a 40A, 120V, 1-pole unit is needed for a dedicated branch circuit.
• Adding a dedicated 120V circuit for heavy-load appliances or equipment in a home workshop or small business setting, while maintaining clear, organized protection zoning.
• Upgrading older panels to modern, thermal-magnetic protection that delivers predictable trip behavior and helps minimize nuisance trips.

Technical snapshot — Square D brand reliability in a single-pole package:

• Manufacturer: Square D
• Part Number: QOB140
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 40A
• Voltage Rating: 120V
• Number of Poles: 1
• Mounting Style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Ideal for electricians and DIY enthusiasts deploying reliable, compatible protection in residential panels, small commercial panels, or light industrial setups. The Square D QOB140 is more than a breaker—it’s a steadfast guardian for your electrical system, delivering predictable protection, solid mounting, and OEM-aligned compatibility. Ready to secure your circuits with confidence? Add the Square D QOB140 to your panel today.