Blue Sea 30-300A Marine Rated Battery (MRBF) Dual Terminal Fuse
Blue Sea 30-300A Marine Rated Battery (MRBF) Dual Terminal Fuse
Dual Circuit High-Amp Protection - Mounts on 3/8" (Approx. M10) Battery Studs - Max 300A
Highlights:Insulating Cover: Flexible red protective cover to prevent accidental short circuits,Mounting Hole: 8mm hole for secure connection to battery terminal posts,Terminal Stud 1: M8 stainless steel stud for primary MRBF fuse installation,Terminal Stud 2: Second M8 stud for dual circuit protection from a single source.
Key features: Dual independent circuits from one battery post, Fits standard M8 battery terminal studs, Max voltage of 58V DC suitable for 12V, 24V or 48V systems, Corrosion-resistant stainless steel nuts and lock washers included, Space-saving design mounts directly to battery terminal.
The dual terminal fuse block accepts two Marine Rated Battery Fuses (sold separately), allowing for independent circuit protection for two separate loads directly from the battery post.
Dimensional diagram detailing height, width, and stud spacing for the BS-2151B dual fuse block compared to the single version.
Installation schematic showing connection to a 3/8 inch (M10) terminal stud and use of 5/16 inch ring terminals. 
DESCRIPTION
Space-Saving High-Amperage Circuit Protection
*Please note Blue Sea fuses are manufactured by Eaton, Bussman or Ionnic and may have labelling of one of these manufacturers on the product and/or packaging.
The Blue Sea Marine Rated Battery (MRBF) Dual Terminal Fuse Block solves one of the most common challenges in marine and automotive electrical installations: limited space. By mounting directly onto the battery terminal, this fuse block eliminates the need for short, difficult-to-install cable runs between the battery and a traditional firewall-mounted fuse holder. This design not only saves valuable room in crowded battery compartments but also reduces resistance and potential failure points in your high-current cabling.
Engineered for demanding environments, this unit is ideal for protecting high-load circuits such as inverters, windlasses, and bow thrusters. With a maximum voltage rating of 58V DC, it is perfectly suited for modern 12V, 24V, and 48V electrical systems found in boats, caravans, and off-grid 4WD setups.
Direct Battery Terminal Mounting
The primary advantage of the Blue Sea Marine Rated Battery (MRBF) Dual Terminal Fuse Block is its ability to interface directly with the power source. It is designed to mount securely onto a standard 3/8" (Approx. M10) battery terminal stud. By fusing the circuit right at the battery post, you ensure maximum safety; if a fault occurs in the main cable running to your equipment, the fuse will blow immediately at the source, preventing potential fire hazards associated with unprotected live cables.
Versatile and Robust Design
Constructed with marine-grade materials, this fuse block is built to withstand the harsh conditions of the Australian outdoors. The hardware includes stainless steel studs and tin-plated copper bus bars for maximum conductivity and corrosion resistance. The unit features M8 (Approx. 8mm) studs for connecting your load cables, accommodating heavy-duty lugs and cabling required for loads up to 300A.
Safety is paramount in high-current applications. The included insulating cap prevents accidental shorts across the conductive terminals, satisfying ABYC/USCG requirements for insulation when installed correctly. The versatile design allows for flexible cable orientation, making it easier to route heavy gauge wire in tight lockers.
Dual Circuit Capability
This model features a dual-terminal design, allowing you to fuse two independent circuits from a single battery post. This is exceptionally useful for running a main DC switchboard feed and a separate inverter charger feed from the same battery bank without stacking multiple ring terminals on the battery stud.
Key Features
- High Interrupt Rating: Safely handles high amperage loads up to 300A.
- Compact Footprint: Mounts directly to 3/8" (Approx. M10) battery studs, saving panel space.
- Voltage Versatility: Rated for 58V DC, suitable for 12V, 24V, and 48V systems.
- Secure Connections: Uses M8 (Approx. 8mm) output studs for secure cable termination.
- Safety Cap: Insulating cap protects against accidental short circuits.
- Corrosion Resistant: Tinned copper and marine-grade stainless steel hardware.
Whether you are refitting a yacht or building a custom tourer, the Blue Sea Marine Rated Battery (MRBF) Dual Terminal Fuse Block provides professional, reliable, and neat circuit protection exactly where you need it.
Secure your high-current electrical system today with this compact terminal fuse solution.
SPECIFICATIONS
Specifications
| Ignition Protected | No |
|---|---|
| Maximum Amperage | 300A |
| Maximum Voltage | 58V DC |
| Terminal Stud |
M8 (5/16") (M8 major diameter 8 mm; 5/16" ≈ 7.94 mm; reference only) |
| Maximum Torque |
75 in-lb (8.47 N·m) (approx. 6.3 ft-lb; reference only) |
| Weight (min / max) |
0.30–0.30 lb (0.14–0.14 kg) (approx. 136 g; reference only) |
| SKU: | BS-2151B |
| Barcode: | 632085021511 |
| Model #: | BS-2151B |
| MPN: | BS-2151B |

















































