Electronic – Using a lower voltage for a replacement fuse

fusesmultimeter

I need to replace a blown fuse in my Tacklife DM02A multimeter.

It says on the back of the multimeter that the blown fuse is F1 250mA 600VAC. Its size is 5mm x 20mm and it has to fit into a clip inside the multimeter. I think it is ceramic because it is not see through.

I have looked for an exact replacement for this fuse and have been unable to find any. Most 250mA fuses seem to be 250VAC and most 600VAC fuses seem to be 500mA minimum.

I know it would be a bad idea to use a higher current rating for the replacement fuse, but would it be okay to use a lower voltage? If I used a 250VAC fuse, say, would that just mean that I can't connect the multimeter to more than 250V? I've only been using my multimeter for simple battery powered circuits so can't think of a reason I would need to test that many volts.

Also, would it be okay to use a glass fuse instead of ceramic if I can't find a suitable ceramic one?

Best Answer

The general rule is to always replace with the exact same type and rating.

Multimeter fuses can be hard to find and expensive because of safety considerations, to meet the CAT II 600V and equivalent IEC requirements.

If you replace it with a lower voltage rated fuse the multimeter will no longer meet the specifications, yet will be marked as meeting them, so it is a bit of a booby trap.

Under no circumstances use a glass fuse, they lack sufficient interrupting capacity even at lower voltages.

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(I could speculate on the possibility that the fuses and meter could be marked in a misleading manner but it's better to be on the safe side).

I suggest contacting your supplier. You're surely not the first one to blow a fuse.