When are fuses required in UK plugs?

March 2, 2016 9:03 AM

I've purchased an aftermarket UK "duck head", the plug adapter used with Apple chargers. I have an official Apple one and it includes a replaceable fuse in the adapter. The aftermarket one does not. This will be used in a 12w iPad charger only (without an AC cord), not a laptop charger. Since there is no AC cord, and the charger is an integrated 12w device, is the replaceable fuse required to meet UK regulations?

Here is an example of the aftermarket part:
http://www.amazon.co.uk/dp/B010C0MH08

It is designed to look like there is a fuse compartment but there is not.

posted by cosmac to Computers & Internet (11 answers total)

Fuses in BS 1363 (the standard UK plugs) are required by law. It'll work, but it might set fire to your house. There's some incredibly thorough websites out there about UK plugs, not to mention the wikipedia article on it
posted by sarahdal at 9:20 AM on March 2, 2016

this would be easier to answer if BS-1363 was freely available, but it's not.

from here: Adaptors enable more than one plug to be put into a single socket, or allow a plug or plugs which are of a foreign type to be used in a UK socket. Adaptors sold for use in the UK are required to meet BS 1363-3;1995, the specification for adaptors. These adaptors MUST be shuttered, if they are for use with non-UK plugs then the adaptor MUST be fitted with a fuse, and they MUST conform to the pin dimensions of a BS 1363 plug.

however, i personally would not care too much. here in chile the voltage is the same (well, 220V) and plugs are not fused (i have an equivalent piece for an apple charger sitting next to me, with no fuse). i haven't died yet. your house is extremely unlikely to burn down from using that adapter.
posted by andrewcooke at 9:26 AM on March 2, 2016

i haven't died yet.

If you had, you wouldn't be here to tell us about it.

This site implies that a) all plugs should have a fuse, and b) your plug specifically should have a 3A fuse:

A common UK plug is generally fitted with a 3A or 13A fuse. For appliances up to 700w you need to use a 3A fuse and for appliances over 700w you need to use a 13A fuse. For example:

3A Fuse – Table lamp, standard lamp, television, video, computer, mixer, blender, fridge, freezer, power drill, jig saw, soldering iron

In this Apple support post (from 2010), someone says:

Cheched the iPad charger and changed the [3A] fuse.

This teardown/comparison between genuine and fake chargers says that genuine iPad chargers have a 2A fuse.
posted by EndsOfInvention at 9:55 AM on March 2, 2016 [1 favorite]

 → here in chile the voltage is the same (well, 220V) and plugs are not fused

It's unlikely that Chile uses UK-style ring main domestic wiring, so that's why fuses in BS 1363 plugs are a good idea.
posted by scruss at 10:26 AM on March 2, 2016 [1 favorite]

Response by poster: The Wikipedia article states:

Other exceptions to the use of BS 1363 plugs and sockets include ... low-power portable equipment (such as shavers and toothbrushes) and mains-operated clocks.

12w is pretty low power.

I don't think it is an adapter as described in andrewcooke's link either (it isn't designed to convert non-UK plugs).

Another way to ask the question: Do all UK 12w USB adapters have replaceable fuses? Do your phone chargers all have replaceable fuses?

Thanks!
posted by cosmac at 2:28 PM on March 2, 2016

OK, found a genuine Apple charger. It has a 3A fuse inside. Given the one you posted to an Amazon link to looks exactly the same but appears to "fake" the fuse socket, I would not trust it.
Photos of my charger: 1, 2, 3.
posted by EndsOfInvention at 2:46 PM on March 2, 2016

that was already mentioned in the question
posted by andrewcooke at 3:28 PM on March 2, 2016

Oh, whoops. Doesn't that answer the question though? Why would they include a fuse if it wasn't required? It's not like that type of plug has wide usage, they make it specifically for the UK, and it would be a waste of money to include unnecessary safety features.
posted by EndsOfInvention at 3:30 PM on March 2, 2016

Also, as far as I can tell, a toothbrush charger is around 2W, so the 12W phone charger is not quite as low wattage.
posted by EndsOfInvention at 3:36 PM on March 2, 2016

Best answer: disclaimer: i have not lived in the uk for some time, so my equipment may be old and no longer legal

i own "wall warts" (transfomers) with UK plugs (ie uk-shaped connectors) that do not have (visible, user replaceable) fuses. i also own similar power supplies with cables which invariably have fused plugs. so my experience is that, as you suspect, at least some devices that connect directly to the wall do not need fuses.

(my intuition is that the fuse is mainly to protect from cable damage, which is consistent with what i describe above, and supported by speculation here).

however, it is not clear to me what this "adaptor" is, in terms of the standard. as i already said, the standard is not freely available (which seems like a really dumb idea, but no doubt saves the govt some tiny amount of money), so it's difficult to give a clear answer. it seems possible that it is considered an adaptor, because it interfaces to another (apple proprietary, internal, female) plug. given that uncertainty i suspect apple "played safe" by including a fuse (it's not like apple owners are price sensitive).

i know logitech, at least, have similar "adaptors" and i would love to know if they are also fused, but i do not own a uk version.
posted by andrewcooke at 4:03 PM on March 2, 2016

Best answer: Do all UK 12w USB adapters have replaceable fuses? Do your phone chargers all have replaceable fuses?

I've just checked three branded adaptors - Samsung, BlackBerry and Amazon (kindle) - and none of them are fused, which was surprising to me. I thought they had to be.
posted by goo at 5:22 AM on March 3, 2016