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Re: [Phys-L] ceramic fuses

I respectfully disagree.
It is my opinion that the CONTACT resistance at the ends of the fuse will be comparable to the resistance of the 1/4 amp fuse itself.
Your discussions (or lack thereof) with the meter vendor reinforces my position (Again - in my humble opinion.)

If the meter manufacturer is in fact using the fuse element as a critical component in the measuring circuit - I'd like to hear about it and recommend another brand of meter.

I'd buy the cheapest 1/4 amp fuse you can acquire.
If the form-factor is right and the voltage spec matches - you're good to go.

Another consideration is slow-blow vs standard vs FAST. (FAST is used to protect delicate expensive stuff - not student meters)


On Aug 20, 2012, at 11:03 AM, George M Caplan wrote:

I would use exactly the fuse specified.
In addition to safety reasons, here's another reason:
The resistance of the fuse determines (in part) the resistance of the ammeter.
If the resistance changes with current as the fuse heats up, the
resistance of the ammeter will not be constant.
This problem exists even when using the proper fuse in at least one
model of Extech multimeter.
I spoke to a very nice fellow at Extech about this. He said he'd check
with engineers.
After I spoke to him twice, he stopped returning my calls.!