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Pond Aerator Pump Protection

Discussion in 'Electrics UK' started by dogfonos, 2 Jun 2021.

  1. dogfonos

    dogfonos

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    I have a pond aerator pump that plugs into mains electricity. In normal use, it draws 4 Watts, evidently. It wasn't supplied with a mains plug so I fitted one and installed the lowest rated mains fuse I had - 2 Amps. However, the instruction manual states:

    "should be fused for a rated fault current of max. 30mA by means of a fault current protection device".

    Maybe I'm misinterpreting this statement but I take that to mean either a 0.03 Amp fuse or MCB?!? They don't exist, do they? Maybe they mean an RCD? An explanation would be appreciated, thanks.
     
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  3. ericmark

    ericmark

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    Yes it means a RCD, is does measure current, it basic measures amps in and amps out and assumes if not equal must have gone to earth 0.03 amps (30 mA) is the standard size.
     
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  4. EFLImpudence

    EFLImpudence

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    They apparently do mean an RCD but that is irrelevant to the fuse rating and the 30mA operating current of an RCD does not limit the fault current which will occur during a fault.

    Fuses are to protect the cables so it depends on the cable rating.

    However, that does not preclude using a fuse lower than that rating - 2A or the usual 3A will be fine.
     
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  5. SFK

    SFK

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  6. JohnW2

    JohnW2

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  7. SFK

    SFK

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    John - made me look. :>
    I have a JCB one to hand, and yes it has a fuse plate and a 13A fuse inside it.

    No idea. Perhaps to safeguard its internal wiring and incase someone plugs in a Chinise infused plugtop.

    SFK
     
  8. JohnW2

    JohnW2

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    Photos show no evidence of a fuse (unless it's hidden on the bottom) - so what does "fused" in the name of the first one (but not the second, which is entitled "unfused") mean?

    upload_2021-6-2_20-50-4.png upload_2021-6-2_20-50-29.png

    Kind Regards, John
     
  9. JohnW2

    JohnW2

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    Oh, I was looking at the wrong one - confusing 'cos the colours of the two (on Masterplug website) were the opposite of the screwfix photos . So it does have a fuse. Very odd!
    upload_2021-6-2_20-54-50.png

    Kind Regards, John
     
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  11. JohnW2

    JohnW2

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    ... and the description of the unfused one (but not the fused one) includes ...
    :?:

    Kind Regards, John
     
  12. EFLImpudence

    EFLImpudence

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    Is that a flex outlet at the bottom - for wiring direct to the appliance and no socket on the other side?
     
  13. EFLImpudence

    EFLImpudence

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    Has screwfix got the fused and unfused the wrong way round?
     
  14. JohnW2

    JohnW2

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    I'm doing well at getting confused and hence confusing everyone else. You're right - the fused one is hardwired and doesn't have a 'socket' to plug into. Whether the one depicted by screwfix ("fused" AND with a socket outlet, described as a 'plug-through adapter) actyal exists or not, I don't know. The front of the fused one of which I recently posted the back view (showing the fuse) looks like this (no 'socket')
    :
    upload_2021-6-2_21-30-45.png

    Kind Regards, John
     
  15. JohnW2

    JohnW2

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    Yep, that's the answer.

    All is now clear (no thanks to screwfix), and the reason for the fuse is clear. Apologies for adding to the confusion!

    Kind Regards, John
     
  16. SFK

    SFK

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    Just to add to the maddness - photos of my JCB 30mA RCD 'Socket' with a 13A fuse in the back.
    Which brings us back to the question



    IMG_20210602_220214699.jpg IMG_20210602_220241436.jpg
     
  17. JohnW2

    JohnW2

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    Quite. It really makes little sense - as you may well agree, the two suggestions you previously offered (as regards 'what on earth is the purpose of the fuse?') seem a little far-fetched - although I can't say that I can think of any better explanations!

    If they were concerned about people plugging in "Chinese unfused plugs", that would be an argument for including fuses in all sockets (two in double ones)!

    Kind Regards, John
     
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