Square D | A1140 | Circuit Breaker | 40A | 1-Pole | 120V | Bolt-On

The Square D A1140 Circuit Breaker is a purpose-built protection device designed for reliable, once-and-done compatibility in maintenance, retrofit, and replacement projects. With exact 40A, 1-pole, 120V specifications, this bolt-on breaker plugs into compatible Square D panels to restore essential overcurrent protection where original components are needed.

Why choose a bolt-on design? The bolt-on mounting delivers a secure, robust connection to the panel bus, reducing the risk of loose contacts and ensuring consistent trip performance. This makes the A1140 a dependable choice for scenarios where a precise, high-amperage 120V single-pole solution is required, whether you’re refurbishing an older installation or replacing a failed unit during routine service.

Key specifications

• Amperage: 40A
• Poles: 1-Pole
• Voltage: 120V
• Mounting: Bolt-On
• Part number: A1140

Specific use cases and benefits

• Repair or upgrade of Square D panels that require a 40A, 1-pole, 120V bolt-on breaker to restore proper circuit protection for heavy-duty 120V circuits.
• Retrofit projects where matching the original part number (A1140) is the cleanest path to compatibility and code-compliant protection.
• Maintenance replacements that minimize downtime by fitting into the same physical footprint and electrical ratings as the existing unit.

How to confirm fit and maximize safety

• Always confirm fit and ratings before ordering. The part number is the most reliable reference for compatibility with your Square D panel and bus configuration.
• Ensure your installation matches the panel’s requirements for single-pole, 120V protection and that the surrounding wiring and terminations are rated for 40A conductors.
• With the main power off, replace only the breaker that matches the existing amperage and pole configuration to maintain balanced protection across the panel.

Who this is for

• Homeowners and professionals performing panel maintenance, retrofits, or replacements in Square D systems.
• Technicians seeking a dependable, brand-backed 40A, 1-pole, 120V bolt-on option that aligns with original equipment specifications.

Why this matters in real-world terms

Choosing the right 40A 1-pole 120V bolt-on breaker means safeguarding high-load circuits without overfitting non-matching components. The A1140 delivers predictable trip behavior, quick installation in compatible panels, and the peace of mind that comes from using a trusted Square D part designed for precise electrical protection.

Ready to restore reliable protection to your 120V circuit? The Square D A1140 is purpose-built for precise compatibility, straightforward bolt-on installation, and enduring performance in retrofit and replacement projects.