Overview
The Siemens D140 circuit breaker is a Type QD low voltage protection device designed for single-pole applications. Rated at 40 amperes and 120V, 60Hz operation, this breaker delivers the dependable magnetic trip protection required in commercial and industrial electrical systems. The D140 is engineered as a direct replacement for Square D type QO breakers and plugs directly into compatible loadcenters without modification.
Key Features
- Type QD classification by Siemens Energy and Automation
- 40-amp rating with single-pole configuration
- 10,000 AIC (amperes interrupting capacity) for reliable fault protection
- Plug-in design—3/4-inch snap-on termination to QO-type bussing
- Square D QO-compatible; direct replacement with no panel modifications needed
- UL Listed for safety and reliability
Technical Specifications
The D140 is configured for standard single-pole protection. Its magnetic trip mechanism responds instantly to short-circuit conditions while thermal protection handles gradual overloads. Load-side connectors accommodate 60/75°C wire, and the breaker is calibrated for 40°C maximum ambient applications. The compact form factor (approximately 1 in H × 3 in W × 3 in D) fits standard loadcenter slots without crowding adjacent breakers.
Typical Applications
- Branch circuit protection in commercial electrical panels
- Equipment shutdown and disconnect in manufacturing facilities
- Expansion circuits when existing breaker capacity is exhausted
- Replacement of aging or failed QO-type breakers in legacy systems
- Residential and light commercial service panels requiring single-pole protection
Compatibility & Replacements
The Siemens D140 is fully compatible with Square D QO brand load centers and serves as an approved replacement breaker. Its 3/4-inch snap mechanism interfaces directly with QO-type bussing without adapters or field modifications. This interchangeability makes the D140 an ideal choice for maintenance technicians and system integrators managing mixed-manufacturer electrical systems. The box of 16 breakers provides convenient bulk inventory for service shops and contractors.
