Can one British plug fuse blow when plugged into a 4G extension lead without the other three doing the same?

Question

Or would the fuse for the whole extension lead blow?

Answer 1

Depends on the value fuses used. Typically, if they are all the same and greater than about 3A, the Extention Lead fuse will blow before the individual plug blows. You'll probably find it's more likely for the whole extension to blow as people are stupid and fit low current devices with 13A fuses!

For example, if you had 4 devices plugged in with 3 devices pulling 4A and had 5A fuses on each and your extension lead had a 13A fuse. As soon as your 4th appliance draws more than 3A current, it will blow the extension lead fuse as the total current draw through it would be more than 13A. In this case, your individual fuse on your 4th device would not blow, because it would not have exceeded 5A.

However, if you had 4 devices fitted with 3A fuses, drawing 2A each and your 4th device had a problem and drew 4A, the individual fuse on the 4th device would blow. This is because the current through the whole extension lead is only 12A (less than the 13A fuse), but through that individual fuse is 4A (greater than the 3A fuse)