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In certain countries (for example the UK), plugs have fuses in them. In most cases, this is a stand 13 A fuse.

My question:

If I know that a device (to which the plug is attached) won't draw even a single Amp of power (or maybe 2amps but definitely less than 3):

  • Shall I replace the fuse inside the plug with a lesser one? for example: a 3 amp fuse.
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Originally, in the UK after BS1363 was introduced, there were 1, 2, 3, 5, 7, 10, and 13A fuses but nowadays mostly 3,5 and 13 are used/available.

The plug fuse is to protect the wire between plug and appliance, it is not primarily intended to protect the appliance (which can have it's own fuse or other protections).

So the choice of fuse principally depends on the diameter of the wires between plug and appliance.

However there is nothing wrong with choosing a lower fuse capacity that will also protect the appliance to some degree.

  • 1
    Remember the SAME appliance will be sold in many countries that don't have fuses int he plugs. – Walker Jan 6 '15 at 17:42
  • thanks @RedGrittyBrick. Especially appreciate the additional input on plug-appliance protection. – Phil Jan 6 '15 at 21:00
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Should you? No, of course not. Most electronics should already have a suitable fuse installed. In some things (kettle leads, extension cables) these fuses are rated high because the end load is unknown.

Can you reduce them? Sure. If you feel something requires extra protection from surges or feel it has been incorrectly rated, you can lower the fuse to the current you think it's going to draw. But many things (especially those with motors) naturally surge so picking too low a fuse rating will result in you changing fuses a lot.

But I wouldn't recommend anybody run around their house changing out all their fuses. If you're really worried, it's might be better to reconfigure your circuits to have more, lower rated mains rings instead of (as many properties have) one or two high rated circuits. Separate the kitchen out and break it down by floor. Getting this right usually results in a total rewire and occasionally needs tweaking but it's good sense to limit total power to some parts of a house (beyond a lazy electician's 32A "ah, screw it, this'll do" breaker).

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The purpose of fuses is not to protect your appliances. The purpose of fuses is to keep your wiring from starting a fire and burning down your house. If your wiring is up to code the fuse will blow long before the wiring has an issue. By reducing the amperage of your fuse you are simply setting yourself up for more headaches and costs from un-necessarily blown fuses.

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