I just managed to cut the lead on my multimeter, so i figured that i would take this opportunity to install an inline fuse on that lead, something that I had been meaning to do for a while. Only when I tried looking up tutorials on how to do this, I couldn’t seem to find any. Could y’all point me in the direction of some? Or give me a brief walkthrough? (If you do, keep in mind that I have minimal electrical experience) I feel like this is a simple task that i am overthinking, but this is the second most expensive tool I own, and I want to make sure that i do this right.
Most quality meters have a fuse inside. Is this for additional protection?
also yes. it’s also a way to fix the cut lead
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They make inline fuse holders. Installation is very easy.
https://www.mouser.com/Circuit-Protection/Fuse-Holders/Fuse-Holder/_/N-axfrp?P=1z0z385
Remember that installing an inline fuse on the lead will also increase the resistance of the lead. It might be minimal, but you won’t have an exactly accurate resistance reading unless you compensate for it.
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Shouldn’t make any practical difference unless reading in the low ohms (<10 ohms). Fuse + holder total resistance should be in the few 10ths of an ohm, max. Now if it’s a really bad fuseholder then all bets are off.
This is true normally, but if you get a spring loaded fuse holder with cheap contacts they can oxidize or the spring can get weak and compact and cause problems. This is especially true if you use a fuse holder that you scrapped off of some other piece of equipment or it’s in a wet or corrosive environment.
Analog or digital meter?
Install a fuse? A good thought but . . .
Most meters are already protected internally with a fuse that may be replaceable but might be difficult to access. The approach is to protect the most sensitive part(s) of the VOM or DMM. For analog, this would be the meter movement and I’m not sure how a DMM does this. Probably uses some form of overvoltage protection plus a fusible device.
I’m rambling a bit but I think you should just go with what is included with the meter. A fuse blows based on current, thus you would have a hard time deciding how to fuse your device. A fuse would not protect the VOM much on overvoltage of the volt ranges (hopefully there is OVP on the analog meter). And a fuse might blow prematurely when measuring current since the meter depends on shunt devices to mostly allow an low impedance path thru the meter.
OK, the best way to phrase it:
- The ideal voltmeter presents an ultra high impedance (open circuit) to your test circuit
- The ideal ammeter presents an ultra low impedance (short circuit) to your test circuit
- There is no way you can externally fuse a lead to do what you want for all or even most setting on your VOM.
As I mentioned - good thought but I can’t think of a solution - perhaps others may have another opinion.
Cheers!
DJ
I totally concur. Current measurement is protected by an internal fuse. With the high impedance for voltage measurement, there would not be enough current to blow a fuse.
If your meter already has a CAT III or better rating, you are unlikely to put in a better fuse holder and fuse than it already has in the ammeter path. And on the other functions, the fuse can’t blow unless the meter has already suffered a major over voltage failure.
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