CBW57 Push-to-Reset Circuit Breaker: Low-Profile Protection for AC/DC Equipment
When equipment needs resettable overcurrent protection in a compact package, a thermal circuit breaker can be a clean alternative to a one-time fuse.
The OptiFuse CBW57 is a low-profile, push-to-reset thermal circuit breaker designed for AC and DC equipment circuits. With ratings from 3A to 30A, support 125/250VAC and 32/50VDC, and a compact panel-mount body, the CBW57 is a strong fit for applications where serviceability and configuration flexibility matter.
Push-to-Reset
The CBW57 is a manual reset breaker. When it trips, the button pops out and the circuit remains open until someone physically resets it.
That makes troubleshooting easier. Instead of replacing a fuse after every trip, a technician can inspect the load and correct the issue. This is useful in equipment where the protective device needs to stay accessible and visible to the user.
Key Specs Engineers Care About
- Current range: 3A to 30A
- Voltage rating: 125/250VAC, 32/50VDC
- Interrupting rating: 1000A at 125/250VAC and 300A at 50VDC
- Reset style: Push-to-reset, manual reset
- UL 1500 Ignition Protection, ideal for Marine Grade applications
Where the CBW57 Makes Sense
The CBW57 is commonly used in equipment where branch circuit protection already exists upstream and the breaker is being used for supplementary circuit protection. This can include:
- Industrial equipment
- Motorhome and RV appliances
- Marine electrical panels
- Factory automation equipment
- Plug-connected AC equipment
- Control panels and auxiliary circuits
Because the CBW57 is a supplementary protector (UL 1077), it should not be treated as a standalone branch circuit breaker. The CBW-style line voltage thermal breakers provide overload protection and must be used with upstream short-circuit protection where required. To learn how UL 1077 differs from UL 489 breakers, see our UL 489 vs. UL 1077 comparison.
A Compact Breaker with Flexible Configuration
One of the main advantages of the CBW57 is how configurable it is.
Depending on the application, the breaker can be specified with different terminal styles, bushing types, button colors, mounting hardware, nameplates, and splashproof boot options. This helps OEMs match the breaker to the electrical requirements and enclosure design of the final product. See the CBW Circuit Breakers Configuration Guide for more details
OptiFuse also offers dedicated CBW circuit breaker blocks for cleaner multi-circuit assemblies. The BLCBW-206 consolidates six independently sourced CBW57 or CBW58 breaker circuits in one compact block, making it useful for boats, RVs, and panels with mixed switched and unswitched circuits. For layouts that need a shared feed and ground bus, the BLCBW-106-G provides a common-source CBW block option. Both are rated 30A per position and 32VDC.
See our Circuit Protective Device Selection Guide for complete context. For application support or fuse selection help, contact OptiFuse at [email protected].
Sebastian Castañeda is a circuit protection specialist and technical writer with application-focused experience in technical support and custom protection design. He contributes practical, application-driven insights to the OptiFuse Blog.