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Technical fuse block wiring

Discussion in 'Traditional Hot Rods' started by 1980gold, Sep 28, 2015.

  1. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

    On my 41 ford chevy engine, that I bought a couple of months ago as I go through the 80s multi colored nightmare of a wiring job under my dash I realize I need to start from scratch because while there is a fuse block under there it isn't connected to anything in the car and there are just a bunch of radio shack inline fuses to everything . I bought a new fuse panel and I want to wire it and start over. My question is the main power going to the box, if I wire up from the battery all circuits will be constant hot? I know I can wire up from a key on hot at the ignition switch so nothing will be on w/o the ignition switch buy how do I do both w/ the same fuse block? I have a blue sea marine block to use I think its st 5035. In the spring I will buy a full wiring kit for it I just want to get it ok till I put it away for the winter.
     
  2. 48fordor
    Joined: Jan 16, 2009
    Posts: 137

    48fordor
    Member
    from York, PA

    My experience with automotive wiring has always been OEM and aftermarket fuse panels have two main feeds, one always hot and one hot with the key on. I'd review the wiring diagram for the car and see how the circuits were originally wired to see how they can be grouped. If it is really a 5035 then each fuse is independent and there is no common bus. Wire each fuse to the correct 12V feed source.
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 43,700

    squirrel
    Member

    That should do it. I put a 4 fuse panel in my Chevy II, and it only uses 3 of the fuses. Two are wired to key on, the other to always on.

    Old cars didn't really need many fuses, but some guys like lots of fancy electric stuff, so they need a lot of fused circuits. Also older (1950s) Chevys had fuses built into the light switch, and the radio and heater had inline fuses. It worked ok at the time, and it still works if you are careful with your wire routing, sizing, etc.
     
  4. rfraze
    Joined: May 23, 2012
    Posts: 1,995

    rfraze
    Member

    When you power the always hot panel from starter lug or battery, protect that circuit with a maxi fuse. Second choice would be a fusible link wire.
    Most panels have provisions for ON input from the key switch at least, sometimes another for ACC input from key. The circuits powered by ACC side go off temporarily during START. Circuits connected to ON side of key stay on when key is in START position.
    If you choose to use separate smaller panels, these can be designated as Always HOT, Key ON, and ACC sourced. This gives you the flexibility of having panels located closer to whatever they power.
     
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  5. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

    thanks guys I appreciate the input. The blue sea # 5026 is what I have so it hae appositive lug which I guess for now I'll go to my ignition switch to make it a key on fuse box. What gauge should I use going into the positive lug?
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 43,700

    squirrel
    Member

    I guess you didn't understand about how each fuse is independent? you can wire half of them to igniton power, and half to constant power. Or however you want. Some things want power all the time, other things want it only with key on.

    general rule of thumb: 10 gauge wire is good for 30 amps, 12 gauge 20 amps. 14 gauge 15 amps.
     
  7. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

     

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  8. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 23,444

    Jalopy Joker
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    How To Wire Your Street Rod, by Jack Sweeden (do not let title scare you away) is a good basic book to have - available from Speedway & more
     
  9. bct
    Joined: Apr 4, 2005
    Posts: 3,008

    bct
    Member

    Looks like the block in the pic is left and right, 6 left 6 right . You could sound it out with an ohm meter.

    id start with a list of accessories for each side and the amprage of each. 125% of the largest draw then 50% of each other draw . Size and protect the wire inline to this . Mount to one side of your block and jump to the other nearby terminals with appropriate wire or copper bus bar. Feed the accessories from the terminals near the fuse.

    Looked again and the top terminals seem already connected . Fuse block could be divided into 4 but not likely
     
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  10. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

    thanks I will give it a shot tomorrow
     
  11. deucemac
    Joined: Aug 31, 2008
    Posts: 988

    deucemac
    Member

    All modern automotive electrical systems use three buss'. Battery, Ignition, and Accessory. Centec makes a good fuse block and it is very simply laid out Battery buss items are for things you want power to all the time, ie. lights and such, Ignition buss is for things you only want to power when the ignition is on, and Accessory buss is used for those items that you want to use when not needing the ignition in the on position. Keep in mind that when you have the key in the ignition "run" position both the ignition and accessory buss' are powered. So run a battery wire to the battery buss and a battery wire from the battery buss to the ignition switch input. From the ignition switch output, run a wire to your ignition buss, and from the accessory output run a wire to your accessory buss. Then from each bus run the wire to the item or system you want to power from that buss. I hope this helps. It is a little short but covers the basics of wiring a car based on buss use.
     
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  12. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

    thanks again. I tried finding internet material on this but as usual the guys on the HAMB helped me thanks again
     
  13. 1980gold
    Joined: Jul 18, 2015
    Posts: 132

    1980gold
    Member

    so I ended up wiring the box to key on hot and bought a small 6 circuit box for the constant hot. Till the spring at least I know all my circuits are fused. I replaced my alternator wire w a bigger gauge without 3 splices and my main power also thanks to everyone for their input
     
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