I made a simple resistance tester for meters that tests them with 1, 10, 100, 1K, 10K, 100K and 1Mohm 1% resistors. I chose 0.5W resistors for the lower ranges and a high voltage resistor for the 1Mohm range to allow for checking insulation testers.
If you want to make a similar tester for electrical installation meters the two most useful resistor values are 1 ohm and 1 megohm. The 1M resistor will need to be rated for 1kV or more for insulation testers that can test at that voltage. It's a good way to check a meter is functioning correctly.
The only time I've seen electrical installation test meters go out of calibration is when they've been abused. Usually involving applying the probes to a live supply and then attempting to do a resistance test on it despite the warning light being lit. Modern meters try to be idiot proof by preventing the test being done, but ironically they are less reliable because of the more complicated circuitry.
The routine calibration thing appeared at the same time as the Part P protection racket was pushed for by organisations who make a LOT of money from it. It's part of the same detached paperwork industry that brought us the five-day electricians certificate. (The same reason meters now need to be idiot proof.)
It's reassuring to see that my old American-made Fluke from around the early 1990's is still reading accurately.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
If you want to make a similar tester for electrical installation meters the two most useful resistor values are 1 ohm and 1 megohm. The 1M resistor will need to be rated for 1kV or more for insulation testers that can test at that voltage. It's a good way to check a meter is functioning correctly.
The only time I've seen electrical installation test meters go out of calibration is when they've been abused. Usually involving applying the probes to a live supply and then attempting to do a resistance test on it despite the warning light being lit. Modern meters try to be idiot proof by preventing the test being done, but ironically they are less reliable because of the more complicated circuitry.
The routine calibration thing appeared at the same time as the Part P protection racket was pushed for by organisations who make a LOT of money from it. It's part of the same detached paperwork industry that brought us the five-day electricians certificate. (The same reason meters now need to be idiot proof.)
It's reassuring to see that my old American-made Fluke from around the early 1990's is still reading accurately.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.
Megger the yellow meter!
You can get replacement lead sets quite cheaply.
I recently bought one of the Parkside (ie. Llidl) auto ranging Multimeters, and I wasn't impressed with the leads, so I got a replacement set (complete with removable crocodile clips), for £8.
This video spookily happened to show up in my feed the day I bought my first Fluke (probably Google doing it's thing). I've finally got over the feeling I need "one meter" that does it all. I have a stack of meters because I'm that lazy I just want one in every toolbox and location I'm likely to need one. Most of my needs don't demand much accuracy so "it's ok" but recently I was trying to investigate an odd unknown AC signal of unknown frequency, and my cheap meters were useless. I realised it was time to finally at age forty something to buy my first Fluke 115 (a "cheap" Fluke 😆) with frequency counter and "true RMS". I have high hopes, and might feel more manly with a Fluke in my toolbox 🤣🤣
I'm kind of glad that we don't have anything similar to part P in the US (or at least none that I know of).
Over the past few years I have successfully recharge non-rechargable batteries. It usually takes a couple of minutes in my smart charger. My electrian friend says its not possible but I've done it dozens of times. Any comment?
Where can I get that box? 😀
i love my cheap meter. Having one in the garage is so much easier than having to go upstairs to get my "better" meter
You must have gone "nuts" building this….
50 years ago the only decent meter you could purchase was an A"vomit"er. I purchased a new one, first of it's kind with flexible ribbon printed circuits in it. Plugged it into a socket. Range was, from memory set at 0-200v. Wrong range. Clicked the dia 1 click to next range. — BOOM. End of meter.
A"vomit"er had fitted make before break wafer switches.
That was the end of my love affair with A"vomit"ers.
Fluke 787 nowadays. – 4-20 simulator built in.
30 years ago an electrician asked me why I always had a Fluke. I swung mine by the leads, let it go.. It bounced off a 4 metre ceiling and hit the ground. Picked it up undamaged.
He bought a 77 next week.
Makes you wonder why you need to get the testers checked for calibration when your old Fluke like mines gets it spot on all the time . I have 2 Fluke 77s for the past 30+ years
I finally got a Uni-T 210E ($50.00) after seeing yours after you got it a while back. I really went through some "gosh, do I really need this" sorts of thoughts but went for it. I really like it, mostly for the DC clamp function.
I still use this Aneng AN8002 ($13.00) for most stuff which I got originally because it could measure capacitance. I thought I was having problems with my home AC unit.
It's interesting, like you've done here, to just compare the two. Just now, I'm finding the Cap test pretty much spot on between the two for a couple beefy AC caps. A 35 + 5 uf 440 / 370 VAC one and a 145 uf 330 VAC one.
Now I'm curious to make a little box like you have for testing resistance.
Great to have a resistor and capacitor reference test bed .Essential
Well, calibration should actually be fine tuning. When you send the meters off to be checked, that is certification, or at least that's how it should be called and how it is called here in Romania. If the meter fails the certification, then it should be recalibrated to meet the specs of the certification.
The high voltage resistance test is for insulation resistance.
Meters used on mains appliances around the home should be CAT 2 rated at least. Measuring mains voltage on wiring directly requires a CAT 3 meter. Measuring at the consumer unit requires a CAT 4 meter. A lesser meter could literally catch fire in your hands.
Cheap meters do not have the isolation to prevent arcing. The arcing is caused by voltage spikes on the incoming mains supply – these spikes typically in the KV range bridge the input by ionizing the air and can cause a meter not designed to protect against this to burst into flames.
As for calibrating meters. This is essential for an electrician because he/she needs to know the resistance to 0.05 Ohms. Even a fraction of an Ohm can cause protective devices like circuit breakers to fail to operate within the disconnection times required by the wiring regulation ( BS 7671) – or to fail to operate at all leaving people susceptible to potentially lethal faults and also the possibility of a fire as excessive cable loading over to long a time period causes the cable insulation to melt and degrade.
The reference to Part P scam is wide of the mark. Calibration tests include RCD performance and high fault current tests (to be sure fault current will trip a circuit breaker) along with the ability of the meter to determine loop impedance back to the substation (Ze) and the impedance of the cabling within the house (known as the R1+R2 test).
therefore it's not calibration merely a test as you say – probably thanks to high reliability of electronics
Big Clive. I understand your disdain for ‘calibration’, my life’s work until Covid struck.
In the 70s and 80s a lot of the better meters (rarely got involved with 4 and 5 digit meters) had different guaranteed accuracies for 1, 2 and 5 years. Our work required that those meters would give the one year accuracy continuously. So in those days calibration did involve annual adjustments to ensure those early 6 and 7 digit meters would give the accuracy the job required.
However, nowadays 7 and 8 digit meters give better accuracy measurements over 5 year periods than those older ones over one year.
Thus people like me are no longer needed. Each year my salary can buy them a new meter plus an outsourced calibration of the old ones.