Fabricating a DIY ANL Fuse Block

Jeff and Anne continue with their thorough refit of s/v Pilgrim.  Here they tackle the fusing of the primary wires in the 12V electrical system.  And they do it right.  Jeff made this as two separate posts, I have collapsed them into one here.

Pilgrim’s progress is crawling towards the installation of the primary DC electrical wiring.  The primary wiring components are:

• Battery Bank(s)
• Large gauge, high amperage wires connecting primary components
• Shunts to allow for the installation of battery monitors
• Switches for directing or cycling on/off the flow of power through primary wiring & components
• Bus Bars to make multiple wire connections in which all the wires are on a common circuit.
• Terminal blocks to make multiple wire connections in which the wires are on separate circuits.
• Terminal posts for making connections in which the wire(s) are on separate circuits.
• Fuses to protect­­­­ the wiring and components from excessive amperage.

We purchased a BlueSea 600A Power Bar to serve as the primary distribution point for the DC positive wiring.  The wiring leading from the positive bus will be fused at the battery box.  A few of the other wire runs will need to be fused proximal to the bus bar.

Simple Diagram of Pilgrim's Primary 12V DC+ Distribution Bus

We are installing  ANL Fuses for Pilgrim’s primary wiring system.  Rather than purchase individual ANL fuse holders for each circuit requiring a fuse “downstream” of the positive bus, we are fabricating our own ANL Fuse Block.

Materials used to create DIY fuse block clockwise from top: Starboard, BlueSea Bus, ANL fuses, 5/16" Stainless Steel Fasteners.

Our fuse block will utilize a ¼” thick Starboard™ base to mount the BlueSea Bus adjacent to a DIY terminal block.  The gap between the bus and the terminal block will be set up to accommodate ANL Fuses.  ConFUSED yet?  Hang in there pictures are worth a thousand words.

Our DIY terminal block will consist of ¾” Starboard™ with 5/16” countersink machine screws as studs.

Laying out the spacing for the 5/16" countersunk holes.

The holes in the ¾” Starboard™ are positioned to match the alignment of the BlueSea bus bar.  The holes are drilled and countersunk to fit the 5/16” machine screws.

Inserting the 5/16" machine screws in the starboard block.

The screws are inserted from the underside of the block with the threaded portion of the screw exposed on the topside.  A washer followed by two nuts jammed against one another secure the screws to the Starboard™ block.

Inserting a couple ANL Fuses between the new block and the prefab bus ensured proper positioning when we mounting the two pieces on the base.

Completed fuse block sans the wires and one fuse.

The bus and the terminal block are held in position by #10 counter sink machine screws capped with lock nuts.  The base extends ¾” beyond the assembly on each side.  This excess base will provides area for mounting screws.

When installed in Pilgrim the fuse block will have large gauge wires and/or an ANL fuse attached to each post.

Mock up of wiring attached to fuse block (still missing one fuse.

The image above is a mock-up of the future installation aboard Pilgrim.  From the top down…

• The upper wire feeds power from the engine alternator when the engine is running.
• The second wire (currently missing an ANL fuse) runs to a BlueSea Systems Automatic Charging Relay (ACR).  The ACR charges the starter battery when voltage in the circuit is between a preset range.  The ACR also isolates the house bank during engine starting.
• The third wire feeds power to our battery & bilge pump management panel.  Here is a link to our previous post: Installing the New Battery & Bilge Pump Management Panel – June 28, 2015
•  The lower wire (labeled “B”) runs to the house bank of batteries.  This wire run is fused proximal to the battery bank.

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After reviewing the installation manuals for the BlueSky 2000E PV Solar Charge Booster, the AirX Wind Generator, and the ProNautic 12.40 Battery Charger, Pilgrim’s DC+ wiring schematic continued to evolve.    The DIY ANL Fuse Holder (see previous post) needed to double in capacity.

Original Fuse Block Design:

Updated Fuse Block Design:

I disassembled the original fuse block; doubled the size of the base; and added a second row of terminals.

Expanded DIY ANL Fuse Block

The missing fuse feeds the Battery & Bilge Pump Management Panel.  We are still figuring out the correct size fuse for this circuit. 

Eager to check out Pilgrim’s DC wiring schematics?  I do plan on posting the wiring diagrams after a few “outside consultants” review my plans.