CQD240 - 40Amp Circuit Breaker

CQD240 - 40Amp Circuit Breaker

The CQD240 Siemens CQD miniature circuit breaker is a 40-amp, 2-pole breaker used in real electrical panels where 480/277V circuits need dependable day-to-day protection. You’ll usually see it inside lighting panels, control cabinets, and distribution boards, especially in commercial buildings that use DIN rail layouts to keep wiring organized and service work more manageable.

In actual field use, this breaker tends to come up during panel assembly, replacements, or maintenance calls. It fits into existing Siemens CQD setups without requiring changes to the rest of the panel, which makes swaps and expansions much more straightforward. The DIN rail mount keeps installation simple and helps everything line up cleanly with other breakers—something electricians notice when working inside a crowded enclosure.

It carries a 14 kA interrupting rating, which is suitable for typical commercial branch circuit protection. The 2-pole design disconnects both conductors simultaneously, which is standard for 277/480V lighting and distribution circuits.

Overall, it’s a straightforward breaker that's used where consistency matters more than complexity—helping to keep circuits protected while maintaining a clean, familiar panel layout that’s easy to work on later.

Key Features and Benefits

• 40 Amp, 2-pole breaker for 480/277V systems
• Siemens CQD DIN rail-compatible design
• 14kA interrupting rating for branch circuit protection
• Simple DIN rail installation and alignment
• Common in lighting and power distribution panels
• Used in commercial and industrial environments
• Fits existing Siemens CQD panel layouts
• 2-pole disconnect for 277/480V circuits
• Practical choice for maintenance and replacements
• Consistent fit within CQD series systems

Technical Specifications

• Catalog Number: CQD240
• Product Type: Miniature Circuit Breaker
• Series: CQD
• Amperage Rating: 40A
• Poles: 2
• Voltage Rating: 480/277VAC
• Interrupting Rating: 14kA
• Mounting Type: DIN Rail
• Application: Branch circuit protection
• Net Weight: approx. 1.499 lb

Material Compliance and Certifications

The CQD240 Siemens breaker is built in accordance with applicable UL and IEC standards for low-voltage circuit protection equipment. It is intended for installation in compatible DIN rail systems and should be installed by qualified electrical personnel in accordance with all applicable electrical codes and the manufacturer's instructions.

Where It Works Best

• Commercial lighting panels
• Industrial control cabinets
• 277/480V branch circuits
• DIN rail distribution systems
• Electrical panel maintenance and replacements
• Building automation systems
• Tight electrical enclosures
• Siemens CQD-compatible installations