EEVblog #373 - Multimeter Input Protection Tutorial
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange answerers link it when explaining how multimeters survive overvoltage or current misuse and why quality meters with proper fusing are safer.
Recommended by 2 people across 2 different months, 2016 to 2022.
What it is
A 40-minute EEVblog episode in which Dave Jones explains how multimeter input protection works, using the Fluke 27 and its service manual as the worked example. It covers fuses, HRC fuses in the current paths, overvoltage protection and physical shielding in a quality meter.
What people said
Strong rec MicroservicesOnDDD · 2020-05 · Electrical Engineering Stack Exchange · on “Learning from checking a 9-volt battery the wrong way with a multitester”
The number one thing you should have learned is how easy it is to create a short circuit with a multimeter. Don't make the same mistake with house current -- it may turn your multimeter into a grenade! Literally! Dave of EEVblog does an excellent multimeter input protection teaching on youtube ( EEVblog #373 - Multimeter Input Protection Tutorial [this video] ) where he explains the different levels of protection, including high rupture capacity (or HRC) fuses that should be in the current testing paths, along with the good physical shielding a quality multimeter incorporates. In order to test current, you are creating a short circuit... If you watch the video, and you haven't heard him say "blow
Recommends Barleyman · 2016-10 · Electrical Engineering Stack Exchange · on “Can a digital meter be damaged when reading resistance but connected to AC voltage”
Short answer, it's perfectly safe for you (*) and the meter. At least when using a quality meter such as Fluke. Fluke is protected up to 1000Vrms on non-current inputs. Obviously 1kV is not safe for YOU but the meter won't mind. Here's the datasheet of the 170 series DMMS [LINK] . Here's a youtube video [this video] that explains more about DMM protection than you possibly would want to know. And here's a link to the Fluke 27 service manual [LINK] he uses as basis. (*) Perfectly safe is probably going too far. According to IEC62368-1, 50VAC rms is safe for "instructed person" i.e. service guys. 30VAC rms is safe-safe. Still, 50VAC is unlikely to harm you in most cases. IEC TS 60479-1 classifies t
Cites akwky · 2022-08 · Electrical Engineering Stack Exchange · on “Digital output protection against accidental contact with 230V AC”
I plan to build a "Wire Tracer" device to identify mystery wires around the house. I found this [LINK] schematic, which uses a NE556 based tone generator and a contact-less receiver. Hopefully it should work something like this product [LINK] . All manufacturers warn against using such a device on mains powered wires. I am aware of this precaution and never plan to allow such a connection. I do own a "Voltage tester" stick [LINK] with proper safety rating and I will test all wires first. Sometimes, though, stuff happens. Somebody elsewhere might flip a light switch or a breaker, blasting my circuit with 230V AC. This opens an interesting design question. How do I make my device blow up reaso