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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?

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  • \$\begingroup\$ If I do a "worldwide" search for "Ceramic fuse" on ebay I a lot of results. You might be able to find a closer match like 300 mA. \$\endgroup\$ – Bimpelrekkie Jun 15 '18 at 13:39
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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.

enter image description here

(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.

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  • \$\begingroup\$ What make is the fuse in the photo? \$\endgroup\$ – Andrew Morton Jun 15 '18 at 13:47
  • \$\begingroup\$ Not my photo, there was no maker's mark visible in the video. It is usually a logo or name embossed into the metal end cap. I don't see a UR file number either. \$\endgroup\$ – Spehro Pefhany Jun 15 '18 at 15:22
  • \$\begingroup\$ I am wondering if genuine 20 mm 600 V fuses exist - I can't find any on the websites of Farnell, Bussman, Littelfuse, or Siba (of course that doesn't mean they aren't there somewhere). \$\endgroup\$ – Andrew Morton Jun 15 '18 at 17:14
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    \$\begingroup\$ @AndrewMorton It's possible they don't in 5x20 (they do in 6.3x32mm), I don't discount the possibility the Asian makers just put the markings there without doing the testing. The manual is a bit evasive on whether it's actually been tested to meet the spec. Personally, for my own use, I would put a ceramic 250VAC fuse in there (and scratch off the CAT markings) because I would never trust a meter like that at even the limits of CAT II. But can't recommend it. \$\endgroup\$ – Spehro Pefhany Jun 15 '18 at 18:40
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If you use a fuse that isn't rated at sufficient voltage then it cannot be guaranteed to properly interrupt a fault current and may continue to arc internally (thus supplying current) until something catches fire.

However, if you informally ask an engineer what he/she might do you'd probably get a more leniant answer but, that lenient answer would assume that the person using the equipment was fully aware of the new limitations imposed when measuring higher voltages.

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