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  1. #1

    Accessory fuses.

    Just finishing up rewiring the boat.
    Got everything individually fused through a fuse box.
    I have all the fuses mixed up and just basically dropping one in to test stuff out.
    What do you reckon for each light etc?
    I have a pair of bilge pumps. Happy to overkill those, I'd rather burn one out then blow a fuse when I need it. They're big, 2000gph and 1100.
    Some internal LED's, stereo, LED nav lights and all round white, and some small LED spotties.
    Cigarette lighter type phone charging socket.
    27meg, and VHF, when I get around to replacing the busted one.
    Oh and a deck wash pump, but I have the instructions, so I reckon it'll say something in there.
    Think that's it.......
    Have to grab some spare fuses and put in the toolbox.

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  2. #2

    Re: Accessory fuses.

    My boat has the following fused circuits per line:
    head lights
    nav light
    cockpit lights
    flood light
    sounder and gps coupled
    bilge pump
    radio and stereo
    aerator
    power outlet

    All of my controls are mounted in a 300 x 250 IP65 plastic junction box.
    All cables run through glands entering and exiting the box.
    In the box there is three silica gel sachets to absorb any moisture that may enter there.
    I carry a full set of spare fuses in that enclosure.
    All fuses are sprayed with silicone to prevent corrosion.
    If you use silastic anywhere on the control enclosure ensure it is completely dry before closing the lid.
    It leaches acid into the air causing corrosion.
    Jack.

  3. #3
    Ausfish Silver Member 552Evo's Avatar
    Join Date
    Jul 2016
    Location
    Melbourne

    Re: Accessory fuses.

    Hi Gford001,
    Without knowing how much of whatever is on each circuit and what size fuses you have itís difficult to be of much help.

    You are going to have to judge how much current each device uses and be mindful that any fuses number one priority is to protect the cable not the device.

    Having said that if the fuse rating for a 2mm sq cable is 20 amps (for example) and the cable only supplies an anchor LED light that draws 0.5 amp then thereís nothing wrong with using a fuse rating less than the cable current rating. Eg a 2amp fuse.

    Another example is - donít go putting a 40 amp fuse in the bilge pump circuit if the cable supplying the pump is 2mm sq.






    Saltwater fishing, boat mad but has a job that gets in the way.

  4. #4

    Re: Accessory fuses.

    Quote Originally Posted by 552Evo View Post
    Hi Gford001,
    Without knowing how much of whatever is on each circuit and what size fuses you have itís difficult to be of much help.

    You are going to have to judge how much current each device uses and be mindful that any fuses number one priority is to protect the cable not the device.

    Having said that if the fuse rating for a 2mm sq cable is 20 amps (for example) and the cable only supplies an anchor LED light that draws 0.5 amp then thereís nothing wrong with using a fuse rating less than the cable current rating. Eg a 2amp fuse.

    Another example is - donít go putting a 40 amp fuse in the bilge pump circuit if the cable supplying the pump is 2mm sq.






    Saltwater fishing, boat mad but has a job that gets in the way.
    Sweet, will use my best judgement then.
    A bit of trial and error.
    Might try to keep the number of different types to a minimum so that I dont end up having to carry heaps.


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  5. #5

    Re: Accessory fuses.

    Fuse the pumps at the manufacturers recommendations. A bilge pump that can be cleared of debris, have the fuse replaced and then be used again is a LOT more useful than one that just burnt out.........ask me how I know . Same for the deck wash. For the electronic devices the fuse ratings supplied by the manufacturer serve to not only protect the wiring in their power cables but also minimise damage (if they are a repairable brand) and should be adhered too as well. Power outlet sockets (cigarette style) are usually 10 amp max. The lights are a case by case basis but the feed wires on most LED fittings these days set your limit for the fuse - I usually use a 3 amp. Spotlights depend on wattage.

  6. #6

    Re: Accessory fuses.

    Quote Originally Posted by scottar View Post
    Fuse the pumps at the manufacturers recommendations. A bilge pump that can be cleared of debris, have the fuse replaced and then be used again is a LOT more useful than one that just burnt out.........ask me how I know . Same for the deck wash. For the electronic devices the fuse ratings supplied by the manufacturer serve to not only protect the wiring in their power cables but also minimise damage (if they are a repairable brand) and should be adhered too as well. Power outlet sockets (cigarette style) are usually 10 amp max. The lights are a case by case basis but the feed wires on most LED fittings these days set your limit for the fuse - I usually use a 3 amp. Spotlights depend on wattage.
    I'll have to have a look. Most is gear from pre rebuild, so I don't have specs.
    Bilge pumps are new, but not sure where I put the paperwork......
    Maybe some googling is in order.

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  7. #7
    Ausfish Bronze Member Ah Me Ting's Avatar
    Join Date
    May 2019
    Location
    Tweed Coast, Northern NSW

    Re: Accessory fuses.

    Quote Originally Posted by gford001 View Post
    I'll have to have a look. Most is gear from pre rebuild, so I don't have specs.
    Bilge pumps are new, but not sure where I put the paperwork......
    Maybe some googling is in order.

    Sent from my [device_name] using Ausfish mobile app
    100% recommend you do the googling and get some specs of the power draw. You really can't do it by trial an error.

    How many switches (circuits) are you running?

    What is the amp rating of the wire you used?

    What will the total load be, in amps, on each 'circuit' if all devices on that circuit are switched on?

    As a very tough guide, LED Nav lights, cabin lights draw bugger all, so say 0.5amp.

    Headlights or spotlights can vary from not much to oh geez really that much.

    Bilge pump, deck wash pump, live bait tank pump, etc will draw more than you think.

    VHF, Sounder, GPS will draw less than you think.

    The trick then is if you have limited switches and circuits you need to balance them by calculating the draw from the devices on each circuit.

    Trial and error will not work as, hopefully your wire rating is way above the total power draw of any one device. So, getting a fuse to blow means you need a device to fail.

  8. #8

    Re: Accessory fuses.

    Quote Originally Posted by Ah Me Ting View Post
    100% recommend you do the googling and get some specs of the power draw. You really can't do it by trial an error.

    How many switches (circuits) are you running?

    What is the amp rating of the wire you used?

    What will the total load be, in amps, on each 'circuit' if all devices on that circuit are switched on?

    As a very tough guide, LED Nav lights, cabin lights draw bugger all, so say 0.5amp.

    Headlights or spotlights can vary from not much to oh geez really that much.

    Bilge pump, deck wash pump, live bait tank pump, etc will draw more than you think.

    VHF, Sounder, GPS will draw less than you think.

    The trick then is if you have limited switches and circuits you need to balance them by calculating the draw from the devices on each circuit.

    Trial and error will not work as, hopefully your wire rating is way above the total power draw of any one device. So, getting a fuse to blow means you need a device to fail.
    Of man. This is getting complicated......
    Now I gotta do maths???
    Hahaha yeah I'll go over it today, really, it should be pretty easy to figure out, I'll have a sit and a think after I drop the kids at school.
    And yeah, my cables are overkill. Way overkill.

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  9. #9

    Re: Accessory fuses.

    So running a quick overview.
    I have 8 things on switches.
    2x bilge pumps.
    All round white LED.
    LED nav lights
    2 small LED spotties
    2 Cabin LED strip lights.
    Cockpit LED's. 2 round ones and 4 strip lights, same circuit. Assuming this draws more then 3amps, as I blew a 3amp fuse in testing.
    Deck wash. Will check the paperwork.
    Other circuits I decided to not run through a switch, as I figured they'll be on all the time, and didn't want to overly clutter up the dash (There's an isolator).
    GPS (Can Google what this needs).
    27meg.
    VHF (when I get one).
    Accessory/phone charger.
    Will do some thinking later.

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  10. #10

    Re: Accessory fuses.

    Just googled the cable, not as overkill as I thought.
    Running 6 amp (2mm tinned) for lights and 16 amp for pumps etc.....
    So I am thinking 5 amp for light circuits, a bit of googling is saying 5amp for bilge pumps too (seems low).......
    Will give that a crack.

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  11. #11

    Re: Accessory fuses.

    When you're dealing with cable sizes you need to be mindful of the units you are using.
    Copper core dia, overall dia inc insulation, CSAs, or an assortment of invented gauges.
    2mm could be anything, on face value I would interpret it as 2mm core dia but who knows?

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