300A Inline Manual Reset Circuit Breaker – 12V to 42V
Description
This 300A Inline Manual Reset Circuit Breaker provides high-current circuit protection for compatible 12V to 42V DC electrical systems. Designed for marine, automotive, caravan and under-bonnet applications, it helps protect heavy-gauge power cables and connected equipment against excessive current and short-circuit conditions.
The inline design accepts 0 AWG (1/0) cable directly, eliminating the need to terminate the cable with conventional ring lugs at the breaker. A manual reset lever and test button provide convenient circuit isolation and reset functionality.
300A Inline Manual Reset Circuit Breaker
Designed for high-current DC installations, this 300A circuit breaker combines over-current protection with convenient manual circuit isolation.
The breaker can be installed close to the battery or power source to help protect downstream cabling against excessive current caused by electrical faults or short circuits.
Key Features
- 300A circuit breaker rating
- Suitable for 12V to 42V DC systems
- Manual reset operation
- Integrated test / isolation button
- True inline cable connection
- Accepts 0 AWG (1/0) cable directly
- No conventional cable lugs required at the breaker
- Suitable for marine and under-bonnet installations
- High-temperature plastic housing
- Suitable for compatible boats, caravans, trucks and 4WD electrical systems
Manual Reset & Circuit Isolation
The breaker is designed to open the circuit when excessive current conditions cause it to trip. Once the cause of the fault has been identified and corrected, the breaker can be manually reset using the integrated lever.
A test button allows the circuit to be manually opened, providing a convenient means of isolating downstream equipment from the power source.
Inline 0 AWG Cable Connection
Unlike circuit breakers that require ring terminals or cable lugs, this model accepts the stripped cable directly into the breaker terminals. The cable is retained using the integrated terminal screws.
The breaker is designed to accept cable up to 0 AWG (1/0), approximately 53.5mm².
High-Current Cable Protection
High-current DC cables connected directly to a battery can present a significant hazard if the cable insulation is damaged or the conductor shorts to the vehicle chassis or another conductive surface.
Installing appropriately selected circuit protection close to the power source can help protect the cable and electrical system against excessive fault current.
4WD Winch Applications
This 300A circuit breaker is not recommended for typical high-current 4WD recovery winches that may draw more than 300A under load.
For these installations, refer to the winch manufacturer's wiring requirements and use appropriately rated electrical protection and isolation equipment.
Sherpa Grunter Boat Winch Applications
This breaker may be suitable for some Sherpa Grunter boat trailer winch installations where operating current remains within the breaker's capacity.
The Grunter may draw up to approximately 400A under high-load conditions, so a 300A breaker may trip when the winch is heavily loaded. Applications involving smaller or lighter boats may operate below this level, but actual current draw will depend on the load and installation.
Because boat trailer winch power cables commonly run from the vehicle battery to the rear of the vehicle, appropriate cable protection is particularly important. Refer to the Sherpa Grunter user manual and wiring recommendations when selecting circuit protection.
Specifications
| Specification | Value |
|---|---|
| Voltage Range | 12–42V DC |
| Current Rating | 300A |
| Reset Type | Manual reset |
| Manual Isolation | Integrated test / trip button |
| Maximum Cable Size | 0 AWG (1/0), approx. 53.5mm² |
| Cable Connection | Direct inline connection |
| Housing | High-temperature plastic |
| Suitable Environment | Marine / automotive / under-bonnet applications |
| Dimensions | 68 x 83 x 35mm |
Installation
Circuit protection should generally be installed as close as practical to the battery or power source so that the downstream cable is protected.
Ensure the breaker rating and cable size are appropriate for the connected equipment, expected current draw and cable length. All cable connections must be correctly prepared, securely tightened and protected against accidental short circuits.
Important: A 300A breaker should not be selected solely because the connected equipment has a maximum current below or near 300A. Correct circuit protection must also take into account cable capacity, expected operating current, transient loads and the equipment manufacturer's requirements.