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| Berni:
Also the question is at what point do you genuinely need a proper fuse in your meter. If you work with only low power things then there is no real danger of using a cheap meter with the cheap fuse it comes with. And if you work with large industrial switch panels designed to carry 1000s of amps in normal operations you obviously shouldn't even come close with anything other than a proper high quality meter with proper fuses. But at what point does a HRC fuse become a must. Like for example a lot of people use meters to troubleshoot there home mains wiring. Is there enough energy in a wall outlet to blow apart a meter? How about the incoming mains in the fuse box? |
| Fungus:
--- Quote from: Berni on July 13, 2016, 05:23:52 am ---Also the question is at what point do you genuinely need a proper fuse in your meter. --- End quote --- This is an elephant in the room. --- Quote from: Berni on July 13, 2016, 05:23:52 am ---If you work with only low power things... --- End quote --- Not only that but the fuse is only in the low-impedance ranges on the meter, ie. amps. If your meter isn't set to an "amps" range then the fuse does nothing at all. You can take it out and the meter will still measure volts, ohms, etc. I can't think of a legitimate reason to connect the meter to a high energy source in the amps range. Bottom line: The fuse is only there for when you're not using the meter correctly. If you're using it correctly then the type of fuse is unimportant. Worry more about them MOVs, PTCs and creepage distances. |
| joeqsmith:
--- Quote from: Fungus on July 13, 2016, 12:19:39 pm ---Not only that but the fuse is only in the low-impedance ranges on the meter, ie. amps. If your meter isn't set to an "amps" range then the fuse does nothing at all. You can take it out and the meter will still measure volts, ohms, etc. I can't think of a legitimate reason to connect the meter to a high energy source in the amps range. Bottom line: The fuse is only there for when you're not using the meter correctly. If you're using it correctly then the type of fuse is unimportant. Worry more about them MOVs, PTCs and creepage distances. --- End quote --- :-+ Agree 100% and this is why I never included the current in my transient testing. Theses HRC fuses are there for safety. |
| Berni:
Yes the fuse is there only for the time when you stupidly forget you are plugged in to amps and try to measure the voltage of a supply. Just when the said supply is a 12V wall wart all you get is a bit of a spark and the wallwart getting warm. When you do this on a giant 3 phase bus bar the result is a huge arc flash and the chard remains of the electrician that did the stupid mistake. Voltage overloads in multimeters are usually not as concerning since you rarely encounter more than 1000V at home and if you do it tends to be low current. So as long as you don't try to measure the output of a microwave oven transformer you should be safe. The question is if a DIYer does the same amps jack mistake in his home mains distribution panel. Could a cheep meter and fuse become more dangerous in such a situation versus a HRC fuse? I personally never have taken care of using only good quality meters on regular household 230/400V mains. I picked up whatever meter was handy, be it my good Agilent or the cheap 20€ rebadger. |
| helius:
It's slightly overstating it to say the fuse is only for when you misuse the meter. If the power-consuming circuit element that you are measuring current for were to fail short, then the meter itself would become the driven device; the fuse protects you from that situation, too. For example, you are using the DMM in amps mode to measure the performance of a dummy load connected to a 1KW supply. What happens when the load fails short? |
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