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Old 06-16-2011
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Fuse Positioning help

OK, so there's been a lot of discussion about fuses. I've been working on the plans for some essential electrical system upgrades on our Sabre 34. We're not rewiring the whole boat, just upgrading in certain areas.

1. Adding a battery charger (don't currently have one)
2. Moving two separate Group 31s into a single house bank, then adding a reserve battery for the other bank.
3. Wiring the alternator and battery charger straight to the house bank, and charging the reserve battery using an Echo charger

In the process of these upgrades, we're doing our best to add appropriate fusing to all wiring going to the batteries. Currently, our boat has very few fuses near the batteries, and none on the primary cables. As Maine Sail has mentioned in other threads, all wires going to the batteries should be fused close to the battery.

As much as I read about fusing locations (and wiring), I'm not sure I have it "right". Below is an image which outlines what I think our plan would be--just the part around the batteries really. Red squares represent MRBF fuses, and the yellow squares would be smaller fuses on non-primary cable (like for a bilge pump or battery monitor). Note that specific fuses sizes are TBD. I'm just trying to get the "layout" together at this point.

The idea here is to have a DC Neg bus on one side of the bank, and a DC Pos bus on the other side, so only one cable actually goes to the battery.

So a couple of questions:
1) Do I only need the MRBF on the cable to the first battery in the house bank, or do I need to put an MRBF on both batteries in the same bank? It seems to me it could be one, if wired so a blown fuse would cut the circuit for both batteries, but I could be wrong.

2) As for the MRBF location for the house bank, is it good where it's shown, or should it be on the POS bus where the cable goes to the Perko Switch? Or both?

3) Does this plan look like a good way to do this, or am I way off base in my understanding of where these fuses should go?

Thanks in advance for the help!
-J

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1984 Sabre 34 Mk I
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