An MRBF terminal fuse mounts onto a specific fuse-holder stud to protect a DC cable near its battery or distribution source. When replacing a Blue Sea holder, count the separately fused outputs and check how the assembly mounts: the 5191 has one fuse position, 2151 has two, and 5196 offers three outputs from a surface-mounted block. The three holders share the MRBF fuse format but are not interchangeable simply because they accept the same style of fuse.
Match the number of separately protected cables
Each MRBF position protects one output. A dual or triple holder does not turn a fuse into a distribution circuit breaker, and the total block current limit still applies when multiple cables are connected.
5191: one output
One fuse position on the common source stud.
2151: two outputs
Output 1
Output 2
Two independent fuse positions drawing from one common source.
5196: three outputs
Output 1
Output 2
Output 3
Three fused outputs in one separate surface-mounted assembly.
Blue Sea 5191, 2151 and 5196 identification
| Specification | 5191 | 2151 | 5196 |
|---|---|---|---|
| MRBF fuse positions | 1 | 2 | 3 |
| Mounting arrangement | 3/8 in battery or bus stud | 3/8 in battery or bus stud | Separate surface mount |
| Maximum block current | 300A | 300A combined | 300A combined |
| Per-circuit limit | 300A | Individual fuse and total block ratings apply | 240A per output |
| System voltage ceiling | 58V DC | 58V DC | 58V DC |
| Protective cover | Included | Included | Included |
| MRBF fuses supplied | No | No | No |
Identify the holder from its product photograph
Compare these exact UsedRVParts listings with the part number on your existing installation. Opening a product shows its specific condition and availability; in-person viewing or pickup, when offered, is by appointment in Kelowna.
MRBF replacement fuses and rating checks
UsedRVParts also lists the 125A 5184BSS and 300A 5190-BSS MRBF fuses. The 125A model is a possible choice only where the circuit and holder are rated appropriately. The 300A replacement must not be used in a 5196 output because its 240A per-circuit limit is lower.
Before selecting a fuse, match the electrical system voltage, required conductor protection, physical fuse format and interrupt rating. An MRBF fuse is not designed to attach directly to an unprotected battery post without its designated insulating holder.
Manufacturer mounting and electrical drawings
Blue Sea provides model-specific diagrams for 5191 single MRBF, 2151 dual MRBF and 5196 three-output block. Consult these for actual stud arrangement, torque requirements, cable-lug clearance and installation sequence before service.