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I busted my multimeter due to improper use (see Why would a multimeter give an unexpected current reading?) and so decided to change the fuse. Annoyingly I can’t seem to find a 15A 1000V 6.3mm x 32mm fuse, and the closest thing I can find is a 15A 250VAC fuse. I was going to go ahead and assume yes, since I’m only ever going to test DC voltages around 24V or below (but you never know, I may use it to test up to 230VAC in future), but I thought I’d check with the experts before happening upon another silly mistake. The multimeter is an Owon OW18E.

Inside Owon OW18E

Also, curiously, the rating on the front says 20A.

External of Owon OW18E

Also, is it likely that a 1000V 15A 6.3mm x 32mm fuse can be purchased in the UK? I've checked all the usuals in the UK (Farnell, RS, etc), but the highest rated seems to be 250V at 15A. Alternatively, I found a 600V at 10A, but so far nothing near 1000V 15A.

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Yes but ONLY on the condition that you don't use your multimeter above the fuse rating of 250V. The problem is that a fuse may arc instead of blowing at a voltage higher than its rating so the protection you're counting on will not be there.

I strongly recommend that if you do this you clearly label the meter with a "250V LIMIT" warning so that you don't forget or someone else who uses the meter is aware.

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  • \$\begingroup\$ yeah, put a "250V CAT II" label over the bit where is says "1000V 600V" \$\endgroup\$
    – Jasen
    Jul 16 at 3:04
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It will reduce the safety of your multimeter, and may perhaps invalidate its safety ratings. A 15 A 1000V fuse is rated to blow at 15 A of current, and will withstand 1000 V across it without arcing or putting you in danger.

By reducing the fuse rating to 250 V, you now have a multimeter that won't keep you safe if it's exposed to a voltage over 250 V. It certainly will no longer be a CAT-III multimeter rated to handle 1000 V operation.

An alternative would be a fuse with a lower rated current, but a 1 kVac rating. You'll risk nuisance trips, but you won't risk your fuses failing to protect you when you need them. A quick search found a few fuses at lower currents and one model that is rated 15 A / 1000 V. Without knowing the dimensions of your meter's fuseholder, it's not clear whether they will match.

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