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Old 04-05-2016, 02:49 PM   #3
kchace's Avatar
City: Brookline, NH
Country: USA
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 1,692
Originally Posted by Panhandler View Post

I would like to install overcurrent protection for the two house banks. 4awg wire was used with a temperature rating of 105c, but the wiring for the banks is bundled. It is my understanding from reading Nigel Calder that an 80amp breaker of fuse would be appropriate on each circuit as they run in the engine space, but then multiply by .7 because they are bundled so ~56 or rounded up to 60a. Calder states that the fuse or breaker should not be right with the batteries due to fumes and corrosion. However, it seems to me that the easiest way would be to put a fuse right on the battery terminal and then run the cable from it. What is the correct way to handle this?

Thanks for the help! This forum has already been an incredible wealth of information!

What about these MRBF Terminal Fuse Blocks combined with 60a fuses? Blue Sea Systems Single MRBF Terminal Fuse Block
The *conductors* running through engine spaces should be derated, and derated further if they are bundled, but regardless of what the wires can "carry" it is prudent to limit the fuses to the max expected circuit current. If after doing the "derating" math the max conductor current is not sufficient, then you will need to upsize the conductors or not bundle them or don't run them through engine spaces.

I have swapped all my battery fusing over to those "Terminal fuses" They are ignition protected, don't require extra wiring, available in 30-300A sizes and take up the least amount of space. BTW - they are made by Buss and available at Delcity for a fraction of the cost from Blue Sea Systems.

Marine Rated Battery Fuse Block

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