Siemens BQ3B040 - 40 A, 240 V, 3-Pole Bolt-On Circuit Breaker | AmpState

The Siemens BQ3B040 is a 40A, 240V, 3-pole bolt-on molded case circuit breaker built to shield your electrical system from overcurrent and short circuits. Designed for panelboards and load centers, it delivers dependable protection with a compact, rugged design that holds up in demanding environments.

Secure, vibration-resistant mounting

Bolt-on mounting provides a rigid connection to the bus, reducing movement and ensuring steady electrical contact even in panels subject to vibration or equipment start-up shocks.

Stable protection with a thermal-magnetic trip

The integrated thermal-magnetic trip unit blends thermal overload sensing with magnetic instantaneous protection. This means predictable tripping under varying temperatures and fast response to short circuits, helping to limit damage and downtime.

Designed for compatibility and versatility

Compatible with matching OEM load centers and panelboards, the BQ3B040 3-pole breaker is suitable for residential, commercial, and light industrial applications. Its 3-pole, 240V configuration supports 3-phase equipment and 240V circuits, enabling streamlined protection in a variety of panel setups.

Key specifications

• Manufacturer: Siemens
• Part Number: BQ3B040
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 40A
• Voltage Rating: 240V
• Number of Poles: 3
• Mounting Style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Use cases and practical scenarios

Install the Siemens BQ3B040 in panelboards or load centers to protect multi-wire 240V circuits and 3-phase equipment. Typical applications include:

• Three-pole protection for 240V motors and HVAC equipment in commercial settings
• Branch circuit protection for three-phase machines in light industrial spaces
• Replacement breaker in residential or small business panels where secure bolt-on mounting is preferred

Why choose this breaker over alternatives

Compared with plug-in designs, the bolt-on BQ3B040 offers superior mechanical security and vibration resistance, reducing the risk of loose contacts over time. The thermal-magnetic trip delivers reliable, repeatable protection across temperatures, helping to prevent nuisance trips or delayed responses that can disrupt operations.

In short, the Siemens BQ3B040 is a purpose-built solution for durable, dependable protection of 240V, 40A circuits in panelboards and load centers—ready for residential, commercial, and light industrial environments.