The Blue Sea Systems 187-Series 120A Surface-Mount Circuit Breaker (Model: 7146-BSS) is a great choice. It combines switching and circuit protection in one device. The single lever operation is clear and easy. It has a 'Trip Free' design that won't stay 'ON' during a fault current. It's waterproof and has recessed mounting holes for a clean look. The large clearance around terminal studs can accept heavy gauge wire lugs, and the 5/16 M8 terminals offer high torque connections. The large lever shows the trip status. It's ignition protected, safe for gasoline-powered boats and meets SAE J1171 requirements. Note: Don't use it as a switch for high inrush currents. Specifications: Amperage is 120A, Max Voltage is 48vDC, Surface Mount. It uses a thermally responsive Bi-metal blade. Terminal Stud Torque is 75 in-lb (8.47 Nm). Interrupt Capacity is 5000A @ 12V, 3000A @ 24V, 1500A @ 42V. Operating Temperature ranges from -40°C to 85°C. Case Material is Thermoset Polyester. It's a Type III - switchable/manual reset - trip free circuit breaker. Mounting Hole accepts #10 (M5) Screw and Terminal Stud Size is 5/16' - 18.
Using this circuit breaker is easy. First, find a suitable surface for mounting and use #10 (M5) screws to secure it. Connect heavy gauge wire lugs to the terminal studs, which have a large clearance for easy connection. The 5/16 M8 terminals ensure a strong connection. When you operate the large lever, you can clearly see the status of the breaker. Remember, don't use it as a switch when there are high inrush currents. For maintenance, keep it clean and dry as it is waterproof. Check the terminal connections regularly to make sure they are tight. The breaker works well in temperatures from -40°C to 85°C, but avoid exposing it to extreme conditions for long periods. If it trips, it will reset manually, just use the lever to turn it back on. This breaker is safe for gasoline-powered boats as it is ignition protected, but always follow all safety procedures when installing it on a boat.
