MRBF (Marine Rated Battery Fuse) holders let a high-current DC cable be protected near its battery or distribution source. Blue Sea's 5191, 2151 and 5196 look like members of one family, but they are different connection arrangements: one terminal fuse, two terminal fuses or three surface-mounted fuse positions with a shared feed. Match the electrical layout before choosing the holder.
One, two or three MRBF-protected outputs?
Each MRBF fuse protects its own outgoing positive conductor. In a multi-fuse holder, those outputs can share a supply but are not separately switchable battery banks. The 5196 is a surface-mounted common-source block; it does not simply stack onto a battery terminal like the 5191 and 2151.
5191 — one fuse
Single protected positive lead with compact terminal mounting.
2151 — two fuses
Two individually protected cable runs. The holder remains limited to 300A total.
5196 — three fuses
Three MRBF positions on one common-source block—not three independent feeds.
Compare Blue Sea 5191, 2151 and 5196
| Specification | 5191-BSS | 2151-BSS | 5196-BSS |
|---|---|---|---|
| Fuse positions | One | Two | Three |
| Supply arrangement | Battery/bus stud mount; one protected output | Battery/bus stud mount; two protected outputs | Surface mount; single common supply with three protected outputs |
| Max DC voltage | 58V DC | 58V DC | 58V DC |
| Maximum block current | 300A | 300A total, not 300A per output | 300A per block |
| Per-output maximum | Up to 300A when correctly protected | Within 300A total limit | 240A per circuit with specified 4/0 cable |
| Main output studs | M8 (5/16 in) | M8 (5/16 in) | M8 (5/16 in–18) |
| Fuse supplied | No | No | No |
| Cover | Protective cap | Protective cap | Clip-on insulating cover |
Blue Sea lists a 75 in-lb maximum stud torque for the 5191 and 2151, compared with 100 in-lb for the 5196. These are model-specific specifications, not blanket values for every MRBF part. The 5196 uses surface-mount M5 (#10) hardware.
Exact Blue Sea MRBF holders in NewRVParts
These are the matching store products with their catalog photos. Open an item for its current warehouse availability and ordering details. NewRVParts products ship from supplier warehouses; viewing and pickup are not available.
Blue Sea original diagrams and dimensions
For actual stud location, mounting holes and assembly sequence, use Blue Sea's dimensioned drawings for 5191 single MRBF, 2151 dual MRBF and 5196 common-source surface-mount MRBF. The 5196 page includes a manufacturer wiring diagram.