Wall-warts

[Steve]

Wall wart transformers with real transformers in them - what protection do they normally contain? Is there a requirement for them to be fused to 13 amps max, as there is with other 3 pin plugs? I have just seen a photo on another website of a UK wall wart where the primary was wired straight to the pins, and the secondary was straight to the output wire. No fuse there at all.

 

[bernardgreen]

Often a thermal fuse is buried in the primary winding. Opens when transformer gets too warm. Some do not reset.

 

[toasty]

Fuses in plugs are there to protect the cable, a wall wart doesn't have a cable.

Most I've seen have a thermal fuse embedded in the primary winding.