I've only seen this happen when the plug was fitted badly (pinched or damaged wires inside the plug) or someone use a nail in place of the fuse. People do stupi

I've only seen this happen when the plug was fitted badly (pinched or damaged wires inside the plug) or someone use a nail in place of the fuse. People do stupid things like that all the time but it's not the fault of the standard, a fuse should blow if it's run over-current for too long.