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What fuse to use

Discussion in 'Electronic Basics' started by palito, Sep 15, 2005.

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  1. palito

    palito Guest

    I have a 12v timer/relay powered by a 12v marine battery. Timer is powered
    by battery and has a relay that passes through the load acting as on/off
    switch. Instructions say to put a 1 amp fuse between power and battery.
    I can only find 1 amp 250v slow or fast acting fuses at Radio Shack.
    Will either the slow or fast acting fuse do the job or is there more I need
    to know to wire this in?



    Check the automotive shops for a 1 amp 12 volt. But it doesn't sound like
    you have any real delicate electronics that you are protecting so I wouldn't
    hesitate to use a 250 volt fuse. When a 250v fuse blows in a 12 v circuit
    it will arc slightly longer than had it blown in a 250V circuit. I would
    use a standard blow fuse which may only be marked 1 Amp / 250V and not
    either slow or fast.

    little fuse 311001 low voltage standard blow 1 amp

    if you can't find them use a fast acting 250V

    Little fuse 312001 250V fast acting 312001.html

    Do not use a slow blow unless you have an inductive load i.e. a motor or
    something else that has a lager start up current.
  3. JeffM

    JeffM Guest

  4. palito

    palito Guest

    Thanks for the info.
    Radio Shack's 1 amp 250v appears to be same as the link you sent so am
    going to use that one.

  5. Tom Biasi

    Tom Biasi Guest

    With that device you are only protecting against catastrophic failure. Stick
    any one amp regular fuse in there as close to the battery as possible. If I
    were doing it I would get a 1 A 12 automotive fuse though.
  6. Jasen Betts

    Jasen Betts Guest

    250V fuses will be fine
    - unlike lightglobes the voltage rating on fuses is a maximum not an

    Slow or fast will make little difference in this application. the main
    purpose of the fuse is to stop a wiring fault from starting a fire or

    Use one of those in-line fuse holders.

  7. Jasen Betts

    Jasen Betts Guest

    What do they look like? I've only ever seen 250V 3AG fuses used in 1A auto
  8. John Fields

    John Fields Guest

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