Siemens ED21B040 - 40 A, 120 V, 1-Pole Bolt-On Circuit Breaker | AmpState

Introducing the Siemens ED21B040 — a 40A, 120V, 1-pole bolt-on molded case circuit breaker crafted to shield your panelboards and loadcenters from overcurrent and short-circuit events. This device is engineered for dependable performance in real-world electrical installs, delivering precise protection when you need it most.

What makes the ED21B040 stand out

• Secure bolt-on mounting: a rigid, vibration-resistant bus connection that stays tight through everyday electrical activity, reducing the risk of loose connections and intermittent trips.
• Thermal-magnetic trip unit: combines thermal protection with magnetic short-circuit sensing for fast, repeatable response across a range of temperatures and load conditions.
• OEM-friendly compatibility: designed to work seamlessly with matching Siemens OEM load centers and panelboards, ensuring coordinated protection and straightforward replacement.
• Versatile applications: suitable for residential, commercial, and light industrial environments where reliable branch-circuit protection is essential.

Technical specifications

• Manufacturer: Siemens
• Part Number: ED21B040
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 40A
• Voltage Rating: 120V
• Number of Poles: 1
• Mounting Style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Ideal use cases

• Retrofit and replace aging breakers in Siemens panelboards and load centers to restore reliable protection for lighting circuits, receptacle banks, and small-appliance circuits.
• Install as part of a residential electrical panel upgrade where a compact, single-pole solution is needed for specific branch circuits.
• In commercial or light industrial panels, protect individual branches that demand dependable overcurrent protection without sacrificing space or performance.

Why it matters for your electrical system

The combination of bolt-on mounting and thermal-magnetic trip behavior means fewer nuisance trips and more stable protection, even under fluctuating loads or elevated ambient temperatures. By choosing a breaker that aligns with your Siemens panels, you ensure consistent trip curves, predictable performance, and straightforward maintenance down the line.

Installation guidance and considerations

• Use in panels rated for 1-pole, bolt-on molded case breakers and compatible with Siemens OEM accessories.
• Ensure proper torque on mounting screws according to panel specifications to maintain the integrity of the bus connection.
• Consult a licensed electrician for panel assessments, especially when retrofitting into existing electrical systems or upgrading multiple circuits.

With the Siemens ED21B040, you get a purpose-built solution that delivers targeted, reliable protection for your critical circuits, backed by Siemens’ engineering for panelboard harmony and long-term safety.