Best clamp meter to get started?

[nicebutdim]

How accurate will the low mA readings be I wonder ?

I had read reviews of other cheap clamps and they didn't seem to be reliable at that type of testing even though advertised as such

I have the same meter from CPC and while I can not attest to its accuracy, it's readings were consistent with those from a TEK775 and pretty much in line with what might have been expected.

Hardly a scientific analysis, but hopefully I'll get to try it alongside more respected names in the near future.

 

[Mikegh]

I have the same meter from CPC and while I can not attest to its accuracy, it's readings were consistent with those from a TEK775 and pretty much in line with what might have been expected.

Hardly a scientific analysis, but hopefully I'll get to try it alongside more respected names in the near future.

Good to know I'll be looking for a leakage tester, have a couple of standard testers

Might splash out a bit when I get back, off with fractured ribs

 

[Mikegh]

I have the same meter from CPC and while I can not attest to its accuracy, it's readings were consistent with those from a TEK775 and pretty much in line with what might have been expected.

Hardly a scientific analysis, but hopefully I'll get to try it alongside more respected names in the near future.

Looking at the mustool meters on bangood too

I do like the idea of displaying waveforms.
Afair they're more expensive for displaying higher frequencies

 

[WallaceP]

Hello,
Personally i would suggest focus on an earth leakage clamp as I think this is more useful that a general clamp meter. Unless you have a specific job in mind that's what I would do with a limited budget

 

[DPG]

Something that sticks in my mind from many years ago, maybe a school science thing I'm not sure, is someone showing two digital clocks. One just had minutes and seconds, the other had extra digits showing tenths and hundredths of a second.

So, the question asked was 'which of these 2 clocks is the most accurate?' - guess what most people said ....

The answer is that everybody said that the one showing the tenths and hundredths of a second was the most accurate. But it wasn't, it just showed more digits.

Anyway, I thought it relevant to the issue of accuracy at low current levels.

 

[ElectroChem]

The answer is that everybody said that the one showing the tenths and hundredths of a second was the most accurate. But it wasn't, it just showed more digits.

Anyway, I thought it relevant to the issue of accuracy at low current levels.

Indeed, if the 3% accuracy rating in the earlier post is true then on the 2A range the screwfix meter could be out by well over 30mA and still in spec. Hardly inspires confidence down to single digit mA leakages.

 

[brianmoooore]

Surely any clamp meter will read the earth leakage if clamped around all the live conductors of a circuit, including the neutral. The magnetic fields of everything will nearly cancel out, however much current is flowing, leaving just the leakage to be measured. The clamp meter will have to measure down to a suitably low current to be of any practical use, of course.
On the subject of accuracy, this falls into two camps. There's absolute accuracy and there's repeatability. It's no great problem if a meter consistently reads 3mA when 5mA is flowing, but it is a problem if the meter reads 3mA on one occasion and 5mA on another occasion, when reading the same current.
Anyone with a few resistors and a knowledge of Ohms law can rough calibrate their own meter as long as repeatability is good.

 

[DPG]

Surely any clamp meter will read the earth leakage if clamped around all the live conductors of a circuit, including the neutral. The magnetic fields of everything will nearly cancel out, however much current is flowing, leaving just the leakage to be measured. The clamp meter will have to measure down to a suitably low current to be of any practical use, of course.
On the subject of accuracy, this falls into two camps. There's absolute accuracy and there's repeatability. It's no great problem if a meter consistently reads 3mA when 5mA is flowing, but it is a problem if the meter reads 3mA on one occasion and 5mA on another occasion, when reading the same current.
Anyone with a few resistors and a knowledge of Ohms law can rough calibrate their own meter as long as repeatability is good.

You will never get accuracy and repeatability at those low currents with a £25 clamp meter. It requires circuit design and component choice such that it would be unfeasible.

 

[Mikegh]

You will never get accuracy and repeatability at those low currents with a £25 clamp meter. It requires circuit design and component choice such that it would be unfeasible.

Sounds about right and there's a reason good leakage clamp meters are a lot more expensive than good general clamps

 

[pc1966]

I have the same meter from CPC and while I can not attest to its accuracy, it's readings were consistent with those from a TEK775 and pretty much in line with what might have been expected.

Hardly a scientific analysis, but hopefully I'll get to try it alongside more respected names in the near future.

The CPC model, the TEK and the DiLOG all look pretty much identical, excluding colour/badges, so I suspect there is one factory and different mark-ups!

I have the DiLOG and it works fine, you get some variation if you move the clamp w.r.t. the two cables you are assessing but it is still returning sane readings.

The spec sheets also tell you what @DPG has said about accuracy, it is 5% and 8 digits on the lowest range. So for zero current you might see anything from 0.0-0.8mA reported, and for 199mA it might be out by 10.8mA either way.

True, for checking RCD trip margins that is still small enough to ignore, but it shows you it is nothing like as low as the 0.1mA that the digital readout might suggest.

The Megger DCM305E is two orders of magnitude better in terms of usable resolution, but then it costs 5 times as much as the CPC model! So if it mattered to me for electronic work or similar where better accuracy was necessary I would get the Megger, but for a handy tool for checking RCD threshold or measuring the consumption of low-power circuits (as well as domestic to 100A+) then the CPC or clones are all good choices.

 

[Marvo]

I'd suggest you look at the frequency respose it can measure currents at, it's nice to have a frequency response above 20khz if you're working on inverter appliances like newer generation washing machines, air con units and fridges. Also you need that higher frequency response when working on lighting circuits supplied by dimmers.

 

[pc1966]

For some motor drives we have I got one of these to use with a basic scope:

CP 35 | GMC-I Prosys CP- 35 Current Clamp, 30A DC Max, AC/DC Adapter, 30 A AC Max, Current Output | RS

uk.rs-online.com

It has a 100kHz bandwidth but for the thyristor bridge sort we have in use you see a lot of 50/100Hz and harmonics as they commutate but it is hard to see the "DC" that is actually moving the motors. So I have designed a low-pass filter along with matching PCB to give me a smoother version, though to my shame I have not got round to actually assembling them yet. This is the design if anyone needs something like it: