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Cheapest and reliable enough clamp for AC leaks

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Hi all, this is my first post and I'm a very noob!  :)
I've got a problem with current leakages in an old house. Light is turned off by anti-electrical shock switch whenever AC leakages go over 30mA and I suspect there's more than just one leakage. I can't afford enough money to buy a good AC clamp to detect low currents and my budget is only 60$. In my scenario I just need a clamp that can detect AC down to 10mA. I guess I don't need anything more accurate, I mean the worst scenario could be 3 points of leakage of 10mA each one.

A friend of mine has bought an ACM92 clamp and it can detect AC down to 2.0mA so it's my best candidate for now.
I searched anyway within this forum and found out that is the uni-t UT210E the most suggested cheap clamp for low AC measurement, isn't it? It's within my budget but when I see all its other functions (V, Ohm, etc) I wonder what's its "real value" only to measure low AC compared to the ACM92 and I'd like to listen to your opinions about that. Another question: I saw you can hack this clamp's bandwidth, could it be an advantage for me in my scenario?
Finally I'd like you to add this Zoyi-Zotek VC902 to this comparison because I saw there're a lot of you using zotek instruments so I'd give a chance to this VC902.

I'd be glad to listen to your suggestions within my budget and for my goal. Thanks in advance.

Hi, welcome to the forum.  :)

Yes, the UT210E is certainly the best documented (and potentially cheapest?) on the forum. It's pretty much a known entity.

Beware of the headline specifications of the Zoyi-Zotek VC902 . Although it looks extremely (suspiciously) sensitive on its current ranges, a look at the front panel shows that the uA ranges are on the sockets and not the clamp.  It looks as if the clamp part is AC amps (600A range?) only. Almost certainly not what you want.

I have absolutely no knowledge of the ACM92, I don't see a manufacturer name. If your friend has one, then you would be best advised to play with that and check it out for yourself. It may be a clone of the UT210 (it's possible to mod the UT210 to 6000 count with an eeprom mod), or based on another chip. It's not an issue for AC current sensing, but for DC, the influence of the Earth's magnetic field is a limitation on ultimate resolution, or at least repeatability.

It is very easy to increase the sensitivity of low cost clamp-on meters. You simply increase the turns count passing through the clamp jaws. You can make a ten or twenty turn coil of the appropriate gauge wire terminated with a screw cage terminal block. You put the wire in which you want to measure the current in series with the coil, put the clamp-on meter jaws through the center of the coil and you’ve now increased the meter reading by the turns count.

Have 10 millamps and 10 turns ? The meter will read 0.1 amps or 100 milliamps. 20 turns with 10 mA and the meter will read 0.2 amps.

The bottom line is you don’t need a super accurate, expensive meter. Sure, it’s easier but if it’s something you’ll only do once, why waste the money? Use some science, it’s free.

Also, welcome to the forum. 

I just tried my UT210E at 50Hz and the minimum detectable is about 6 mA.  And yes, adding turns works well but might not be convenient.


--- Quote from: Grandchuck on October 13, 2021, 07:55:57 pm ---And yes, adding turns works well but might not be convenient.

--- End quote ---
Convenience is a function of your access to a single current carrying conductor - and that could be a problem from the outset.  Just to clarify (in case you may not be aware) clamp meters work on the magnetic field generated by current flow.

If you have both current carrying conductors (live and neutral) passing through the jaws, you will have equal current in opposite directions which will result in the magnetic fields cancelling out .... giving a meter reading of zero.  You have to have only one conductor passing through the jaws.

This is how putting one conductor through the jaws several times (ie looping it) gives you higher readings ... because the current is running in the same direction, the magnetic fields add together.  If you want to check plug-in appliances, you can easily make an "extension" lead which has a free conductor and give that conductor enough length to do a number of turns.

So to get the correct current in this example, you divide the displayed value by 5.  Using the 30.00A value displayed in this image, the actual current flowing through the wire would be 6.00A.

Change the number of loops and you change the number you divide by.


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