boat fuse block I made

Discussion in 'Electrical Systems' started by sdowney717, May 16, 2015.

  1. sdowney717
    Joined: Nov 2010
    Posts: 955
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    Location: Newport News VA

    sdowney717 Senior Member

    Since this 1970 boat never fused any 12 vdc mains as OEM, I decided to think of a way to do this. We had replaced a 1960's fuse distribution panel and it had some parts of interest, like long copper buss bars and this black plastic thing. And I like to make things.

    I decided to use two AMG BUSS Mega fuses, one 150 amp for feeding the house loads, one 100 amp to feed Lectrasan, and one 350 amp to feed the 3000 watt inverter.

    I found BUSS AMG Mega fuses for $2.70 at Rock Auto, cheapest place I could find to buy.
    The other white fuse is a heavy built super fast semiconductor fuse from Ebay for $9, made by Littelfuse.
    All these fuses have hole spaces of 2 inches. The semiconductor fuse position could be modded to accept a class T fuse of 1 7/8 inch hole spacing. All these fuses are well sealed.

    I started by welding together the copper bars, but although that was working, it was taking too much heat. So then I started brazing, but that was not much easier. So I bought some Harris 15 silver brazing sticks and that was perfect. these bars are doubled up in thickness, so 1/4 inch by 1 inch in profile. So now all the parts are as one piece. I imagine this fuse block could handle a full power load all at the same time.

    The holes are all tapped to 5/16 and the bolts are SS cap screws from worn out zincs. The bolts hold all the copper buss bars tight to the plastic base. The incoming power is 3/8 bolt. The wire lugs will just bolt down on top.

    I had to modify the plastic base somewhat to an acceptable configuration.

    It turned out well I think. I certainly would not recommend people do what I did as it was a lot of effort, but my costs were just the fuses, a tube of epoxy, and 2 sticks of Harris 15 and a couple weeks of my on and off time. So i am in it for right at 30$.


    I thought about DC breakers but realized I am unlikely to ever blow any of these big fuses.
    The feed line to this fuse block comes from the selector switches which will be right above it.
    So now the only unfused power in the boat is the engine starters.

    So you buy the same fuse at Blue Sea, or pay a lot less at Rock Auto.
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Are those fuses spark proof? In my experience that type gets hot enough to ignite flammables.
  3. sdowney717
    Joined: Nov 2010
    Posts: 955
    Likes: 54, Points: 28, Legacy Rep: 274
    Location: Newport News VA

    sdowney717 Senior Member

    Yes, they are. Blue Sea sells the same fuse.

    the semiconductor fuse is also a heavily sealed part, it is fiberglass resin wound about 1/8 inch thick shell and is totally sealed. That fuse has a good air space all around it. And the plastic base is that type of unmeltable plastic you find in distribution panels. The epoxy I used in various places was JB Weld which has a 500* rating.

    Semiconductor fuses and Class T fuses are made of silver alloy with sand, they are made in the same way.
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