| Products > Test Equipment |
| Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter ) |
| << < (38/43) > >> |
| joeqsmith:
I have no reason to measure my line voltage. I can just look at the lights and see if they are dim. If I want to look at some sort of device hanging on the line, I tossed together a simple box with a transformer and current sense so the equipment is isolated. I use these cheap meters on the bench and while I may frequently run experiments in excess of a kV, it's hardly a concern. When I benchmark the meters, while the generator's outputs are not directly connected to the mains (for safety), the small one is still 20J. Not the most safe thing to play with but I have a fair bit of safety designed into the system. The scary one in the half cycle simulator as we are now around 600J. Photonic Induction would call me a chicken but I use a chicken stick any time I use that thing and keep the outputs shorted when not in use. I consider it CAT1 but by no means that that suggest it is safe to play with. I've shown various loads including meters, fuses and light bulbs attached to that generator. Hardly any concern about an arc flash at 600J. It will cause a light bulb to shatter. |
| joeqsmith:
--- Quote from: IanB on April 27, 2023, 02:34:25 am ---.... Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically. --- End quote --- I think I mentioned I had to repair our microwave a while back. Turned out the fuse had popped. Sent the wife out to pick up a new one and when I get home, I get the story of how the parts store wouldn't sell the fuse to her. The told her they wouldn't sell any parts for the microwave because of the hazards. People die playing service man with them. Wife begins to tell them that she had watched me pull trip the CB before opening it. Then how I showed her all the bits and how I made a few comments about the design and why things were laid out the way they were for safety. Then she tells them about this long stick I had used to touch some things inside before I did anything inside. They said your good, and sold her the fuse. :-DD I can't blame them. |
| rsjsouza:
I love this story, Joe. My wife would probably be able to tell the same details, although the trick is in the convincing and assuring tone... :-DD |
| joeqsmith:
--- Quote from: floobydust on April 27, 2023, 04:34:29 am --- --- Quote from: Fungus on April 27, 2023, 03:52:04 am --- --- Quote from: joeqsmith on April 27, 2023, 12:39:49 am ---My home has a tiny little service coming into from a small distribution transformer. Nothing like what feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one. Worse thing that will happen if I pull an outlet and short the wires, I blow a CB. Hardly CAT III or risk of an arc flash. --- End quote --- Same here. That's why I wasn't worried about measuring the mains with my Big Clive special. Knowledge is power. --- End quote --- Ignorance is bliss. Like a chinese fortune cookie, "May your multimeter's spacings be auspicious". I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts. Or we can argue it's the requirements at fault - the IEC overvoltage categories are wrong. Not that the product has ever been tested or evaluated to meet its fake claims. Strange for EE's to discard science for a cheap "trashy" cause. "Hardly CAT III" you'd need to run a Dranetz to convert speculation and gut feel to fact. I've used loggers in facilities to see if power is a problem with equipment failures. Like making a measurement with some test equipment :-DD --- End quote --- It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison. I want to be clear that those measurements have nothing to do with the high voltage experiment I ran with the two DT830s. Those power supplies will have far less energy available than my small transient generator. And as I said, the DT830 presented enough of a load on the one that the current folded back and we could only reach 1.1kV. So that's 1.1kV/1Meg or 1.1mA. Is that's scary stuff for a meter? Depends on the energy available. Basically, I am referring to the output filter on these supplies. If I placed some large, low ESR capacitors directly across the supplies output and let them charge up before attaching the meter. As soon as I connect the meter, the current is no longer limited to 1.1mA. The energy is 1/2 CV^2. So a 33uF cap would provide around 20 Joules. I posted a link the the DOE safety guidelines and I'm sure all the safety minded folks like yourself understand there is some risk working with even 20J. Will it explode a hand held meter, hardly. Could it kill you, sure. Does what I show have anything to do with AC mains measurements or safety standards, not at all. Let's see your data. |
| joeqsmith:
--- Quote from: rsjsouza on April 29, 2023, 01:35:15 am ---I love this story, Joe. My wife would probably be able to tell the same details, although the trick is in the convincing and assuring tone... :-DD --- End quote --- :-DD I'm sure if you put your wife and mine in a room, they would have similar stories to swap. |
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