Fitting Fusebox

Discussion in 'The Beginner' started by cymap, Jul 6, 2010.

  1. cymap

    cymap Read Only Funster

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    Hi all, I am in the middle of a semi conversion on my transit. I am fitting a leisure battery with a split charge system and a fusebox. My question is what amp wire do i use from the Pos of the leisure battery to the fusebox. Thanks, Mark
     
  2. scotjimland

    scotjimland Funster Life Member

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    Hi Mark

    in order to give an accurate answer we need to know what you what the maximum load is.

    eg
    how many lights, and what wattage, are they LED or incandescent.
    water pump
    12v sockets, for TV any other 'toys' , laptop, etc

    Within reason, the supply cable can never be too big , so do some sums and add in say 10% as a safety margin .. I would guestimate about 25A


    hth
     
  3. Terry

    Terry Funster

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    Hi cymap and welcome :thumb: IF I am understanding your question right, then normal 2.5amp (not 25amp ) cable will be fine. Same type as you use wiring a house socket :thumb:
    terry
     
  4. scotjimland

    scotjimland Funster Life Member

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    Hi Terry , I think you are confusing cable size (in sq mm ) with current carrying capacity ...

    Also, you shouldn't use domestic cable in a van, ie twin and earth , you should use multi stranded flexible
     
  5. hilldweller

    hilldweller Funster Life Member

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    The reason being because solid copper conductors work harden with the vibration then snap.

    Worse, just before they snap they become NOT 2.5sqmm but maybe 0.25sqmm and if they are carrying a load of current at the time they are going to get HOT.

    So Terry, is your motorhome going to catch fire some time in the future ? Give it some serious thought.
     
  6. hilldweller

    hilldweller Funster Life Member

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    I was thinking of another tack...

    Add up all the fuses in the box and there is your answer.

    If you want to assume that not all will be used to capacity then de-rate the cable to a good estimate.

    You must in all cases fit a fuse next to the pos terminal rated the same or less than the feed cable to protect cable. This fuse could then blow if your current estimate is out but the cable will not burn.
     
  7. Terry

    Terry Funster

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    :Rofl1: not mine Brian :thumb: my mate did all the wiring -- if it was me doing it, it would still be at the ripping out the ambulance wiring stage :Rofl1: - that is why I said IF :Doh: - me thinking wiring the 240v leccy fusebox :Rofl1:
    Don't worry about mine Brian SWMBO does not let me touch anything other than plug the kettle in :Rofl1:
    It has been trouble free for nearly 4 years -- has yours
    terry
     
  8. hilldweller

    hilldweller Funster Life Member

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    But I/We do. A fire is no laughing matter. 4 years means nothing if there is flaw there just waiting to upgrade itself to a disaster.

    An electric kettle is just about the worst case scenario along with an electric heater, even a perfect cable starts to rise in temperature with those.

    Mine is fine at 7 years, full of great thick German cable that could serve as a tow rope in an emergency.
     
  9. Terry

    Terry Funster

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    Glad to hear that Brian, British vans have difficulty getting from the factory to the dealers problem free :Rofl1: I know 3 dealers and they all moan about faults on new vans :Eeek: that they have to fix before selling
    terry
     
  10. hilldweller

    hilldweller Funster Life Member

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    They seem to treat dealers as grade one mugs who become the final QA testers and finishing department. Totally unacceptable in my books.

    We bought this Burstner second hand so no idea of any warranty work but I've been just about everywhere inside, adding flexible cables, and have nothing but praise for the quality.

    Some years ago I bought a Rover 25 Turbo Diesel. It was a great fun car to drive with surprising performance. But quality - oh boy - my wife thought I having affair with someone at the Rover dealer. I don't think welding the roof on should really be done by the dealer, but it was. Must be a British thing.
     
  11. scotjimland

    scotjimland Funster Life Member

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    Once you have determined the max load either by Brian's method or mine , makes no odds, here is useful and easy to use calculator to determine the cable size required ..

    http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

    An example to show how the cable size increases with the length.

    For a 25A load with a cable length of 1 mt you require 6 mm cable

    increase the length to 2 mt and you require 10 mm

    and at 3 mt. it is 16mm

    So, when choosing a location for the fuse box bear this in mind ..
     
    Last edited: Jul 6, 2010
  12. cymap

    cymap Read Only Funster

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    Hi Guys, thanks for the replies. I will be using a 12v 19" LCDtv, The aldi mini satellite and a coolbox which is 48watts at 12v.

    Ps can I earth my leisure battery via the earth on the crank battery bearing in mind I am installing a split relay charge jobby. Thanks again, Mark
     
  13. scotjimland

    scotjimland Funster Life Member

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    yes , if that is the most convenient place. I assume you are mounting the leisure battery under the bonnet rather than in the habitation. ?
     
  14. cymap

    cymap Read Only Funster

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    Hi The leisure battery will be under the drivers seat as the crank battery on a transit is under there aswell (Room for 2). Thanks :thumb:
     
  15. Terry

    Terry Funster

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    Hi cymap, just asked my mate (to make sure :Rofl1: ) he says it may be worth mentioning to you that you can earth anywhere suitable (chassis / bodywork ) in your van - ie that means if you run a live cable from front to rear the neg can be connected to the rear,thereby eliminating a cable all the way back to the front -- if you get my drift --IF I have understood him correctly
    terry
     
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