Fuze is an American spelling of fuse, but not for every meaning of fuse. Here it is the part that makes a bomb, shell, or missile go off — a timer, a hit switch, or an old string of powder that starts the fire. US military and technical writing often chooses fuze with a z for that device, and keeps fuse with an s for the little wire in a plug that dies to save a machine from too much power. British English usually writes fuse for both. Though actually, even in American English, ordinary people still type fuse most of the time; fuze shows up on army pages, engineering notes, and older labels. If you see fuze, you are almost certainly looking at explosives, not household electricity.