Square D A1B140 40A 1-Pole 120 V Circuit Breaker Potential Transformer

Meet a trusted name in electrical protection—the Square D A1B140. This authentic Square D circuit breaker is engineered to guard your 120 V circuits with a precise 40 A rating on a single pole. When reliability matters, you want a part built to exacting standards, and the A1B140 delivers consistent performance, protection, and peace of mind for your panel setups.

• Part Number: A1B140 — authentic Square D replacement part
• Current rating: 40 A
• Pole: 1-pole
• Voltage rating: 120 V
• Application: Protects a single 120 V circuit from overload and short-circuit conditions
• Durability: Built to deliver reliable tripping behavior, helping to prevent wiring damage and electrical fires

Why this model stands out is its exact spec alignment with many 120 V, single-pole protection needs. The Square D A1B140 provides predictable, timely interruption when currents exceed safe levels, helping keep appliances, lighting, outlets, and other 120 V loads safe and functional.

Ideal use cases

Residential feeders, lighting circuits, small appliance circuits, or any 120 V branch circuit that requires a dedicated 40 A protection device. It’s a practical choice for replacing a blown breaker or stocking a ready-to-install spare for compatible Square D panels.

Quick installation and best practices

Before replacing, ensure compatibility with your electrical panel and confirm the circuit’s amperage requirement. With the power safely shut off, swap in the A1B140 for a straightforward, single-pole installation. If you’re unsure about panel compatibility or electrical work, consult a licensed electrician to ensure code-compliant installation and safe operation.

Designed for reliability in both home and light-commercial environments, the Square D A1B140 40A 1-Pole 120 V circuit breaker is a precise, durable choice when you need dependable overcurrent protection for 120 V circuits.