Blue Sea 7139 50A 187-Series Surface Mount Breaker

The Blue Sea Systems 7139 is a 50 amp surface mount breaker in the 187 Series, rated to 48 volts DC.

Fifty amps matches 6 AWG cable in typical marine service, which is what makes it a common size rather than an arbitrary one. Sizing the breaker to the conductor is the whole principle. The cable is what burns if a fault is not cleared, and the equipment on the end is usually protected by its own fusing anyway.

Surface mounting puts the breaker on the face of a bulkhead rather than through it, so no cutout is needed and nothing structural gets weakened. That is often the deciding factor in an engine space, where the surfaces available are rarely panels.

A thermally responsive bi-metal blade gives Type III protection with manual reset and trip free operation. Interrupt capacity runs 5,000 amperes at 12 volts DC, 3,000 at 24 and 1,500 at 42. Waterproof, ignition protected to SAE J1171, with a lever that shows trip status by its orientation. Explore more marine circuit breakers.

• 50A, matching 6 AWG in typical marine service
• The cable is what burns if a fault is not cleared
• Surface mount needs no cutout at all
• Nothing structural gets weakened