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Purchased 12v 5a power supply for CCTV - what fuse

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  • 30-08-2020 4:43pm
    #1
    podgeandrodge
    Registered Users Posts: 5,843 ✭✭✭


    Hi, I purchased a 12v 5a power supply

    https://www.amazon.co.uk/gp/product/B00C676JNM

    for a 4 camera cctv system as the original power supply (rated same) failed, which had a 2 prong cable (not kettle) and a 3a fuse, but I can't be sure that this cable was the original that came with the cameras so perhaps the 3a was too small a fuse.

    The new power supply doesn't come with the kettle lead - and I was wondering what fuse should be used with a kettle lead i.e. 13a or just 3a as I read that anything under 700w uses 3a. But if the power supply is 5a would that not blow the 3a fuse :confused:


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    #2
    Cerco
    Registered Users Posts: 2,041 ✭✭✭Cerco


    You should be fine with a 3A fuse in the plug. Don’t confuse the input current at 230volts with the output current at 12volts. They are related but dependent on the design of the power supply.


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    #3
    podgeandrodge
    Registered Users Posts: 5,843 ✭✭✭podgeandrodge


    Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
    I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!


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    #4
    LenWoods
    Registered Users Posts: 617 ✭✭✭LenWoods


    there are C13 to Figure 8 Adaptors available online if that helps;
    the only difference is the earth
    link: https://www.amazon.co.uk/Almencla-Kettle-Female-Power-Adapter/dp/B07V6JRH4V/ref=sr_1_23?dchild=1&keywords=figure+8+to+c13&qid=1598803726&s=electronics&sr=1-23

    pmxb0jZtj

    C13 is king though,
    ive fitted C13 cable to the rear of all my television wall installs,
    i then have some C13 to Figure 8 Adaptors on standby, if the television takes a Figure 8 cable then i can easily adapt the C13 to suit,

    pn3ZqE2xj


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    #5
    Cerco
    Registered Users Posts: 2,041 ✭✭✭Cerco


    podgeandrodge wrote: »
    Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
    I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!

    You use the standard 13A plug but replace the 13A fuse with a 3A bought separately. You can buy a pack of mixed fuses e.g. :

    https://www.woodies.ie/catalogsearch/result/?q=Fuses

    The input current is less than the output current.


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    #6
    alan4cult
    Registered Users Posts: 1,583 ✭✭✭alan4cult


    podgeandrodge wrote: »
    Thanks Cerco. I don't see many kettle leads online with 3a fuse - would 6a be ok? I presume 13a is not safe then as it would not blow?
    I still can't figure out why a 3a fuse wouldn't blow if there is 5a output?!
    The fuse is on the input side only. Also the 5A is DC and supplied at a lower voltage (12V). So as the previous poster said don't confuse input and output current.


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    #7
    coylemj
    Registered Users Posts: 25,462 ✭✭✭✭coylemj


    Cerco wrote: »
    You use the standard 13A plug but replace the 13A fuse with a 3A bought separately. You can buy a pack of mixed fuses e.g. :

    https://www.woodies.ie/catalogsearch/result/?q=Fuses

    You'll get a lot more than four fuses on a card for €1.50 in the pound shops.


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    #8
    Ronin247
    Registered Users Posts: 1,256 ✭✭✭Ronin247


    Watts is the measurement of power and is calculated by multiplying volts by amps.

    The watts remain the same so a 60watt power supply with a 12v output is 60/12= 5amps output

    The input is 240 volts but still supplies 60w so
    60/240= 1/4 amp input so 3 amp fuse is more than enough.


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