Wouldn’t it be great to see at a glance whether a fuse in a plug has blown without needing to test it? Ferraz Shawmut, a company in Massachusetts, has the answer (W0 02/45110).
Its fuse consists of a ceramic tube, inside which is a wire strip of low resistance that’s designed to melt when current flow exceeds a specified limit. That much is standard. But the outside is painted with a red dye, on top of which is an aluminium coating. This has a thin spot, of high electrical resistance. Normally, a current takes the path of least resistance,…
