What is the difference between ceramic and wire fuses?

Answer 1

Wire fuses are just that, bare wire between two posts/fixings. They come in current ratings which relate to its diameter like 5 ampere, 10, 15, 30 etc. Its old style. The wire can run through a sleeve of what used to be asbestos or just an underlay the wire rests on. This is to help prevent/suppress fire.

Ceramic, cartridge fuses, are safer as the wire is enclosed. So the fire risk is gone. The wire runs inside a ceramic sleeve like lead in a pencil. They are more closely rated too in that the 'blow' current is closer than the open wire types and they can be made with really low current ratings, say 1/2 amperes or less.

When a fuse 'blows' people say its a faulty fuse. In fact it did its job admirably. If it did not blow some other wiring in the installation would overheat and maybe blow and cause a fire. The fuse is a definite weak part of circuits to break the current flow that would otherwise cause mischief. So its not a 'faulty fuse', its a faulty circuit.

Don't just replace a fuse - it almost for certain means there is a fault that needs finding. A fuse may melt not blow violently. This is because it is passing more current than it is designed to but not a lot more. If a fuse blows with a bang it has been subject to a very much higher current than designed to carry. Probably a short circuit.

I have known very old fuses fail, in the true sense of the word, through carrying the correct current. This is age and oxidation and maybe even by being tightened to its posts too tightly. Any electrician knows that you dont put in new fuse wire tightly.

Modern safety devices are trips that can be re-set. They can be thermal types that overheat and trigger it to switch off. A bit slow these.

There are also magnetically operated trips that work very fast indeed. The trip has probably tripped because of a fault, a short, or overload. Be prepared for it to immediately trip again when you switch it back on/re-set. Don't keep doing this - get the circuit meggered/tested.

G4CIR