Siemens CQD145 - 45 A, 277 V, 1-Pole Circuit Breaker | AmpState

Meet the Siemens CQD145—a reliable, single-pole molded case circuit breaker engineered for dependable branch-circuit protection in panelboards and load centers. Rated at 45A and 277V, this compact unit is built to handle everyday electrical demand while delivering precise protection that electricians can count on in residential, commercial, and light industrial settings.

Why the CQD145 stands out on the job

• Space-efficient design: Its compact molded case form fits neatly into crowded panel spaces, helping you maximize panel capacity without compromising protection.
• Thermal-magnetic trip unit: Delivers stable, repeatable protection by combining thermal overload sensing with magnetic short-circuit tripping, reducing nuisance trips and ensuring fast response when faults occur.
• OEM-ready compatibility: Seamlessly matches Siemens panelboards and load centers, simplifying replacements and upgrades with consistent performance and fit.
• Versatile voltage rating: 277V rating broadens use for commercial lighting, equipment circuits, and other 277V applications commonly found in today’s facilities.
• Clear specification for decision-making: A straightforward 1-pole, 45A, 277V configuration that clearly aligns with branch-circuit protection needs in a variety of environments.

Technical specifications at a glance

• Manufacturer: Siemens
• Part Number: CQD145
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 45A
• Voltage Rating: 277V
• Number of Poles: 1
• Application: Branch circuit overcurrent and short-circuit protection in panelboards and load centers

Ideal for

• Electricians upgrading or replacing aging breakers in Siemens-compatible panelboards.
• Small to mid-size commercial spaces with 277V lighting circuits and general branch circuits.
• Light industrial installations where reliable protection and space efficiency matter.
• Residential projects that rely on compatible Siemens protection devices for consistent performance.

Practical uses and scenarios

In a office suite or retail environment, the CQD145 can guard lighting and receptacle circuits, preventing damage from overloads or short circuits. In light industrial settings, it provides fast magnetic response to sudden faults, minimizing equipment downtime. Its OEM compatibility means you can confidently source this exact replacement for existing Siemens installations, reducing compatibility questions during retrofit projects.

Installation tips and best practices

• Verify that your panelboard accepts 1-pole molded case breakers from the CQD family and is rated for 277V circuits.
• Ensure proper shutoff procedures and lockout/tagout before replacement or installation.
• Use within its 45A rating to protect branch circuits that draw current within safe limits, preventing nuisance trips and equipment wear.
• Consult project documentation to confirm that the CQD145 is the correct form factor for your Siemens-compatible load center.

Why this Siemens breaker is a solid choice

The CQD145 is more than a basic protection device—it's a purposeful choice for reliable, predictable performance in real-world electrical systems. The combination of a robust thermal-magnetic trip unit, space-conscious molded case design, and seamless OEM compatibility translates to smoother installations, fewer compatibility hassles, and clearer maintenance planning. For projects that demand dependable protection without sacrificing panel efficiency, the CQD145 delivers.

Available from AmpState, the Siemens CQD145 provides a precise, proven solution for safeguarding branch circuits today—so you can install with confidence and keep systems running smoothly tomorrow.