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Circuit Breaker 300A Inline


Suitable for some winch installations, these inline breakers are rated to trip at 300 amp. They are marine rated so suitable for installation on boats, caravans, 4x4 and trucks including under-bonnet installations.


300A Manual Reset Circuit Breaker

These waterproof circuit breakers will detect high amperage draws exceeding 300 amps and will fail open. Users can easily reset them with the toggle of the manual reset lever. They feature a test button which breaks the circuit instantly isolating downstream appliances from the upstream power source.

Being a true inline breaker these units don't require cable lugs to be fitted and rather simply insert the cable end directly into the breaker and tighten the grub screw to retain it.

These breakers are ideal for protecting cables from loads exceeding 300 amps. The breaker will withstand short peaks over 300 amps but will generally break at the rated setting. The breaker itself is housed inside a quality high temperature plastic housing which helps to reduce the impacts of radiant heat from the surrounding environment altering the trip rating.

We do not recommend these breakers for use with your 4x4 winch as these are generally rated to draw in excess of 400A. Users should consider a manual isolator switch for their 4x4 winch or a 500 amp fuse.

These breakers are suitable for use with our boat winches under certain applications. Again your boat trailer winch is rated to draw up to 400 amps however for many smaller or lighter weight boats you are unlikely to exceed 300 amp draw. In these scenarios users many benefit from a 300 amp circuit breaker.

Running a breaker, fuse or isolator is especially important with the boat trailer winch as the power cables are run a longer distance from the engine bay battery to the rear of the vehicle. If this cable was to short circuit as a result of rubbing or even in an accident, a fire could be started. A circuit breaker or fuse installed close to the power source (battery) will protect against these scenarios and protect the cable and vehicle. Refer to the user manual and recommendations provided with your boat trailer winch for further information on wiring. 

Technical Details

Specification Value
Voltage 12-42 V
Rating 300 Amps
Cable inputs 0 AWG (1/0) 53.47mm2
Operating environment Marine / Under-bonnet suitable
Dimensions 68 x 83 x 35mm


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Customer Reviews

Based on 2 reviews
Bryan Casey

Finally a winch breaker that works properly.
After trying 2 other breakers which failed under load I installed the breaker from Sherpa and it is awesome.

Great Circuit Breaker..

Bought this online at Sherpa and installed it in my caravan. Works perfectly and is a very compact unit.