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Thread: Fuse amperage

  1. #1
    Senior Member
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    Fuse amperage

    I came across an interesting post on the European forum. It mentioned changing fuses 6 and 7 to 25 amps, fuse 14 to 25 amps, fuse 15 to 30 amps. Is anyone running this configuration?
    DMCF rebuild 2008, Stage II, Eibach

  2. #2
    Delorean Guru
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    #6 is for Hazard, horns, and door buzzer, supposed to be 20 A
    #7 is the infamous fuel pump, Lambda system and CPR. Supposed to be 20 A
    #14 low beams
    #15 high beams each 20 A
    The wire gauge can only handle 20 amps of a continuous load. A 20 A fuse can handle 15 amps continuous load. These circuits are continuous loads. If everything is working as it should you should not need more than a 20 A fuse. If a 20 A fuse blows or melts it is an indication that something is wrong and should be fixed. The "fix" is not to put a bigger fuse in unless you are doing it as an emergency, temporary fix to get home. That said, on most cars the headlights are protected by a circuit breaker that can automatically reset so you can get the lights back so you can continue driving. Once a fuse blows it cannot "reset" like a circuit breaker. IMHO you should not be changing the fuses to higher than recommended ratings. This is not like the uprated circuit breakers for the cooling fans. That is not a continuous load. At least it is not supposed to be.
    David Teitelbaum

  3. #3
    LS Swapper Josh's Avatar
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    With fuses and the fuse box melting being a common occurrence, this seems like a terrible idea.
    Not to mention if the wires are old and oxidized you are asking for problems.
    Fuses are there to protect the wiring and the components in the circuit. If you are blowing fuses, the solution is never to upsize.

    Once again, this is awful advice.

    5.3L LS4 + Subaru 6spd 314whp/348ft-lbs
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  4. #4
    DeLorean Club UK DeLoreanGo Arran's Avatar
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    This was I believe based on an age-old discussion on the old .com forum, and the old German forum - neither of which are there anymore, with the only remaining info being here: - bottom of the page. In a nutshell, someone in Germany did some tests and found that those 4 fuses (14 and 15 in particular if non-original modern H4 bulbs are being used) were a) running close to their continuous limit and b) as a result getting *very* hot. By upping each of these 4 fuses by 5amps the heat is reduced significantly. So it wasn't to cure blowing fuses, but melting fuses - and really only mainly on the headlights if you are using 60 watt bulbs.
    Granted this is at the expense of continuous load protection if the load was for some reason exactly 4 amps higher than it should be, but a short or massive overload would still blow the fuse.
    With the advent of LEDs and newer fuel pumps, it is probably less of an issue now anyway, as long as you have a properly maintained fuse box.

  5. #5
    Senior Member Bitsyncmaster's Avatar
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    The EU guys have to have headlights that are approved to pass their MOT testing and most of those are 50 watts or more. So that is why they up the fuse that gets hot with the headlights. They have had those headlight fuses melt.
    Dave M vin 03572

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