ACB-H Auto-Reset Circuit Breaker: Compact Protection for Auxiliary DC Circuits
Auxiliary circuits on work trucks, RVs, marine craft, and emergency vehicles need protection that is compact and easy to mount. The OptiFuse ACB-H is a shortstop-style thermal circuit breaker designed for low-voltage DC systems.
The ACB-H uses a Type I automatic-reset mechanism. When an overcurrent heats the internal element beyond its trip point, the breaker opens the circuit. After it cools, it automatically resets and restores power. This makes it useful where a temporary overload may clear on its own and replacing a fuse would be inconvenient.
Compact Horizontal-Bracket Installation
The “H” in ACB-H identifies its horizontal mounting bracket. This integrated bracket allows the breaker to be secured directly to a panel, bulkhead, or vehicle surface, while two #10-32 studs provide straightforward ring-terminal connections.
The ACB-H is available from 5A through 50A for 12VDC, 24VDC, and 32VDC systems. It is tested to SAE J553 and meets SAE J1171 ignition-protection requirements, supporting use in vehicle and marine environments where flammable vapors may be present.
Typical applications include:
- Lighting circuits
- Small pumps
- Fans and ventilation equipment
- Accessory outlets and auxiliary controls
The ACB-H also distinguishes its terminals by function. The copper-plated stud is used for the battery connection, while the zinc-plated stud connects toward the auxiliary load.
Automatic Reset with an Important Limitation
Automatic reset helps restore operation after a brief overload, but it should not be treated as a repair for a persistent fault. Repeated cycling indicates that the circuit should be inspected for excessive load or damaged wiring.If you’re unsure why a breaker continues to trip or how to identify the underlying cause, see our guide, Why Does My Circuit Breaker Keep Tripping?, for a detailed explanation of the most common reasons and troubleshooting steps.
With its metal body, horizontal bracket, ignition-protected construction, and reusable reset function, the OptiFuse ACB-H provides a practical alternative to one-time fuses in compact auxiliary DC circuits. If you’re considering replacing a fuse with a resettable circuit breaker, read our guide, Can I Replace a Fuse with a Circuit Breaker? to understand compatibility, ratings, and installation considerations.
To read up on more circuit protection context, see our Fuse Selection Guide. 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.