I've just purchased a mains to 10amp cigarette lighter adaptor. The seller (based in the UK) in his ad, assures purchasers that it comes with a UK 13 amp plug.

However, upon receipt of the item, it came with some strange 2 pin USA of Chinese mains plug with very small gauge wires. He cannot replace as his supplier has let him down so he's offered a discount so that I can purchase the correct lead locally.

I suddenly though that if the adaptor is rated at 10 amps, what sort of fuse should there be in the UK mains plug as there's only a choice of 3, 5 or 13 amps? The adaptor is supposed to be powerful enough to run an electric tyre pump but the fuse in that is rated at 15amps.

Most other adaptors on the market are only rated at 5 amps.

Randa

If you think there's anything even remotely shonky about what you've got, I'd try it with a 5 amp fuse first.

It's better the fuse goes than the thing itself followed rapidly by your house and all the tinder-dry countryside within a two mile radius.

.

Randa, other fuse sizes are available. In the past I have bought 10 amp. I believe they should be black in colour as opposed to the brown for 13 amp.

Colin

I've thought about this a bit more. The 12V output is rated at 10A which equates to 120 Watts.

So that same 120 Watts is drawn from the mains input - plus, say 20% for converter losses - so call it 150 Watts drawn from the mains which is about 1/2 Amp.

If your adapter is one of those cheap Chinese incendiary devices, you want to use the lowest rated BS1362 fuse available, and that will be 1 Amp.


I came to this conclusion all by my own self, just in case anyone was wondering.

.

P.S. Righty tighty, lefty loosie.

.

Thanks all for your answers. Although we always use the W = A x V rule at the appliance end (eg. cookers, fridges etc) it didn't dawn on me to use it at the adaptor.

So, as John says, it's pulling .625 amps.

Just found this easy calculator therefore saving the maths. https://www.supercircuits.com/resources/...-amps-converter

Randa