Cautions When Using 2007/2008 MRBF Terminal Fuse

December, 19 2007

This technical brief only applies to MRBFs (PNs 5191 & 2151) built prior to 2008. Units built before 2008 are shipped with fiber washers. Newer units do not require the insulating washer and allow for multiple ring terminal connections.

The MRBF (Marine Rated Battery Fuse) Terminal Fuse provides practical, easy and economical circuit protection. Terminal Fuses provide circuit protection in tight space constraints.

Prior to 2008


After 2008

Cautions. Please follow these cautions when installing and using MRBF Terminal Fuses:

  • Terminal Fuses must be used only with a Terminal Fuse Block.
  • There can be only one circuit connection to a Terminal Fuse.
  • The shank of the fiber washer must seat inside the cable end ring terminal.
  • Ring terminals cannot be smaller than 3/8" (M10) or bigger than 1/2" (M12).
  • If the ring terminal makes contact with the terminal fuse stud, the fuse is bypassed and is not protecting the circuit (there is a short circuit across the fuse).



Overview of Product Features and Specifications. The high interrupt rating of this compact, high-amp fuse—10,000 Amperes at 14 Volts—makes it suitable for DC Main circuit protection on large battery banks. It is also ideal for inverter, windlass, and bow thruster circuit protection. Because of its weatherproof construction, it can be installed in open-cockpit boats and other harsh environments. And it is ignition protected, making it safe for installation aboard gasoline-powered boats. Terminal Fuses are available in 15 current ratings from 30A to 300A. Fuses are color coded by amperage, and they have a clear window that provides a visual indication of blown condition. They provide a solution for satisfying the ABYC 7" circuit protection rule*. This compact fuse, approximately 1" by 1" by 1/2", mounted in the Terminal Fuse Block, can be installed on 3/8" (M10) terminals on batteries, battery switches, or busbars.



While MRBF Terminal Fuses provide practical, easy and economical circuit protection, care must be taken when installing and using them.

* ABYC E-11.12.1.1.1. Each ungrounded conductor connected to a battery charger, alternator, or other charging source, shall be provided with overcurrent protection within a distance of seven inches (175mm) of the point of connection to the DC electrical system or to the battery.

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