Which clamp meter to buy?

[jumpjamesjump]

Doing more and more consumer unit changes and think it’s worth while to have an earth leakage clamp tester.

My MFT is a megger which I quite like, so eas going to go with a DCM305E but then noticed that the DCM340 is a fair bit different, ehat’s the difference?!

They both appear to do AC and DC. I potentially want to take on more commercial work in the future so would one have an advantage in larger installations?

thank you very much

 

[snowhead]

DCM 340 isn't earth leakage.

 

[ChipFanDave]

DCM 305 for Earth leakage.

 

[Phil Thompson]

DCM305e for earth leakage

 

[MJPD29]

I have a fluke 360. Mot sure they are in production anymore but probably a new model. Never let me down.

 

[jumpjamesjump]

DCM 340 isn't earth leakage.

DCM 305 for Earth leakage.

DCM305e for earth leakage

I have a fluke 360. Mot sure they are in production anymore but probably a new model. Never let me down.

Thank you all for the replies.
Re-looking at the specs, I notice that it doesn't actually do DC current. Do any clamps detect DC?

Also looking at some of the Fluke clamps and they're £500+ each I see they can detect up to 600amps, I'm guessing that's the main advantage? Can't see anything else spectacular about them.

thanks again

 

[pc1966]

You can get DC clamp meters but they typically cost a lot more than the AC sort (need to use Hall effect sensors or similar, not just transformer action), for example:

CP 41 | GMC-I Prosys CP41 Clamp Meter, 40A dc, Max Current 40A ac CAT III 300V | RS

uk.rs-online.com

Unless you work a lot on DC systems (PV solar maybe, cars, etc) it is unlikely to be very important. More important in most cases for an electrician is a clamp meter that can go down low enough for earth leakage testing as already mentioned. I ended up with one of these when it was on some special deal:

DiLOG DL6518 Earth Leakage Current Clamp Meter

DiLOG DL6518 Earth Leakage Current Clamp Meter The DiLOG DL6518 Earth Leakage Current Clamp Meter is capable of precise earth leakage current measurement, suitable for finding low earth leakage current that could be responsible for nuisance tripping on RCDs. The 18th edition wiring regulations...

www.test-meter.co.uk

[automerge]1587111785[/automerge]
While a good multimeter will give you more accurate current readings than most clamp meters, it is far more hazardous to connect a meter in-line with the circuit. Some loads may take switch-on surges that can damage meters (or at least blow the extra-fast fuses usually used to protect those that are CAT-III or above rated) so for practically all things high-power AC use a clamp meter for checking consumption as well.
[automerge]1587111986[/automerge]
Just to add, this one looks very much like the DiLOG one I have but is currently almost half the price:

Test Meter PRO TMP775 Earth Leakage Clamp Meter

Test Meter PRO TMP775 Earth Leakage Clamp Meter Specially designed for measuring AC earth leakage, the Test Meter PRO TMP775 Earth Leakage Clamp Meter offers a high resolution of 100µA and 3 ranges making it a great tool for general fault finding. Offering a low range of down to 200mA, a mid...

www.test-meter.co.uk

[automerge]1587112308[/automerge]
Note by more accurate a typical camp meter might be 2.5% or so, a good multimeter might be 1.5% AC , so it is not an issue for most practical purposes.

 

[telectrix]

here's a megger 305.

Pardon our interruption...

 

[pc1966]

here's a megger 305.

LOL! It is cheaper on their web site instead of eBay

Megger DCM305E 100A TRMS AC Earth Leakage Clamp Meter

0.001 mA resolution, Up to 100 A AC TRMS readings Jaw size of 40 mm

www.tester.co.uk

 

[Phil Thompson]

Same price as the site sponsor, Megger DCM305E Earth Leakage Clamp Meter - https://www.test-meter.co.uk/megger-dcm305e-earth-leakage-clamp-meter/

Maybe give them a call and see if they can do anything for you.

 

[ruston]

Test meter give forum members a discount . 5% I think.

 

[jumpjamesjump]

You can get DC clamp meters but they typically cost a lot more than the AC sort (need to use Hall effect sensors or similar, not just transformer action), for example:

CP 41 | GMC-I Prosys CP41 Clamp Meter, 40A dc, Max Current 40A ac CAT III 300V | RS

uk.rs-online.com

Unless you work a lot on DC systems (PV solar maybe, cars, etc) it is unlikely to be very important. More important in most cases for an electrician is a clamp meter that can go down low enough for earth leakage testing as already mentioned. I ended up with one of these when it was on some special deal:

DiLOG DL6518 Earth Leakage Current Clamp Meter

DiLOG DL6518 Earth Leakage Current Clamp Meter The DiLOG DL6518 Earth Leakage Current Clamp Meter is capable of precise earth leakage current measurement, suitable for finding low earth leakage current that could be responsible for nuisance tripping on RCDs. The 18th edition wiring regulations...

www.test-meter.co.uk

[automerge]1587111785[/automerge]
While a good multimeter will give you more accurate current readings than most clamp meters, it is far more hazardous to connect a meter in-line with the circuit. Some loads may take switch-on surges that can damage meters (or at least blow the extra-fast fuses usually used to protect those that are CAT-III or above rated) so for practically all things high-power AC use a clamp meter for checking consumption as well.
[automerge]1587111986[/automerge]
Just to add, this one looks very much like the DiLOG one I have but is currently almost half the price:

Test Meter PRO TMP775 Earth Leakage Clamp Meter

Test Meter PRO TMP775 Earth Leakage Clamp Meter Specially designed for measuring AC earth leakage, the Test Meter PRO TMP775 Earth Leakage Clamp Meter offers a high resolution of 100µA and 3 ranges making it a great tool for general fault finding. Offering a low range of down to 200mA, a mid...

www.test-meter.co.uk

[automerge]1587112308[/automerge]
Note by more accurate a typical camp meter might be 2.5% or so, a good multimeter might be 1.5% AC , so it is not an issue for most practical purposes.

thank you for all the useful information.

The Di-log one you have detects down to 100micro amps which if I am not mistaken is 0.1 mA. The Megger is boasting that it "has a resolution of just 0.001mA and excellent accuracy of ±1% (depending on current magnitude)", so essentially can detect an earth leakage of 100 times less and over twice as acurately I mean I doubt this is ever going to be important factor but this at first glance seems to be a sign of a superior product. Reckon their claims are a little misleading?

As for the 6 ranges that the Megger has, compared to the others having 3 or so, I mean this doesn't really matter as long as I know the difference between 0.01 and 0.0001 right? xD

thank you again

 

[pc1966]

The Megger is DMC305e is a better specification than the DiLOG DL6518E (or the even cheaper TEK775 that looks identical) but also costs more, so you need to ask yourself if it is money well spent?

Generally for most electricians work (leaving aside R&D labs, etc, where anything is possible) you would be looking at two uses:

• Current consumption (clamp on only L, or only N)
• Earth leakage (clamp on both L & N to see residue)

For current consumption you are probably worried about if a load is close to (or above) the MCB or switch rating so probably you would be looking at 1-100A in a domestic situation and normally you would want to be able to see a bit above the expected range, so going to 200A is a reasonable upper limit here.

For earth leakage you are going to see RCD that are mostly rated at 30mA, a few incomer that are 100mA, and a few special area that are 10mA. So when testing at the cables to the appliance or RCD/RCBO you would want to measure down to 1mA with decent accuracy.

Most digital meters have a combination of % and digits as the "accuracy" so in my DiLOG meter's case it says the lowest range is 200mA, resolution 0.1mA, and accuracy 2.5% + 8 digit. So for very low currents it is possibly 0.8mA out, but for something like 10mA it would be 10 * 2.5% + 0.8 = +/-1.1mA max error. That is still adequate to check if a circuit is close to the trip threshold for practical RCD cases.

Some boast lower settings so you can measure appliance leakage at low levels, as if doing a PAT test, but that is an unusual approach as if you are needing to do PAT testing it is far better to get a proper tester for that role, such as this sort of thing:

Seaward Primetest 100 PAT Tester

The Battery powered Seaward Primetest 100 PAT Tester is a quick and easy to use PAT tester. The Primetest 100 gives readings as well as PASS & FAIL readouts, ideal for the novice user.

www.test-meter.co.uk

 

[jumpjamesjump]

The Megger is DMC305e is a better specification than the DiLOG DL6518E (or the even cheaper TEK775 that looks identical) but also costs more, so you need to ask yourself if it is money well spent?

Generally for most electricians work (leaving aside R&D labs, etc, where anything is possible) you would be looking at two uses:

• Current consumption (clamp on only L, or only N)
• Earth leakage (clamp on both L & N to see residue)

For current consumption you are probably worried about if a load is close to (or above) the MCB or switch rating so probably you would be looking at 1-100A in a domestic situation and normally you would want to be able to see a bit above the expected range, so going to 200A is a reasonable upper limit here.

For earth leakage you are going to see RCD that are mostly rated at 30mA, a few incomer that are 100mA, and a few special area that are 10mA. So when testing at the cables to the appliance or RCD/RCBO you would want to measure down to 1mA with decent accuracy.

Most digital meters have a combination of % and digits as the "accuracy" so in my DiLOG meter's case it says the lowest range is 200mA, resolution 0.1mA, and accuracy 2.5% + 8 digit. So for very low currents it is possibly 0.8mA out, but for something like 10mA it would be 10 * 2.5% + 0.8 = +/-1.1mA max error. That is still adequate to check if a circuit is close to the trip threshold for practical RCD cases.

Some boast lower settings so you can measure appliance leakage at low levels, as if doing a PAT test, but that is an unusual approach as if you are needing to do PAT testing it is far better to get a proper tester for that role, such as this sort of thing:

Seaward Primetest 100 PAT Tester

The Battery powered Seaward Primetest 100 PAT Tester is a quick and easy to use PAT tester. The Primetest 100 gives readings as well as PASS & FAIL readouts, ideal for the novice user.

www.test-meter.co.uk

Thank you very much for the reply that was everything I wish to know, much appreciated